NATO Is Dead, Long Live NATO? Canada Needs a Plan B

 When historians look backwards, February 2025 will mark the rupture of US-European relations.  Vice President J.D. Vance’s speech at the Munich Security Conference, an affront to all Europeans except the far right, was sandwiched by Secretary of Defense Pete Hegseth’s statement that the US would no longer be the primary guarantor of European security and President Donald Trump’s negotiating away all of Ukraine’s bargaining chips with no Europeans present.  The future of NATO is bleak, as the alliance relied on the US security guarantee, and that no longer seems to be in place.  The next German Chancellor, Friedrich Merz, has started conversations about adapting to the end of the US security guarantee by perhaps tying Germany to France’s nuclear deterrent.  The question then is: where does Canada fit as NATO either disappears or becomes something else entirely?   Canada actually has a vote on this and a role—the transatlantic link, the North Atlantic in NATO’s name—can be fastened on this side to Canadian territory instead of American.  While others have focused on investing more in Canada’s military or leveraging its oil, my argument here focuses on a diplomatic strategy. 

What is the threat to Canada?  To be clear, while the potential alliance of US and Russia is most alarming, the most likely threat to Canada and its sovereignty is not an American invasion but yet more economic coercion.  To deal with that, Canada needs help.  Another target of Trump’s territorial ambition, Greenland, has produced an alliance within the alliance—Denmark has gained the support of the other Nordic countries and the Baltics via intense diplomacy.  Canada should exert as much diplomatic effort as it can to get the European members of NATO do something similar—to agree that any further economic warfare directed at Canada by Trump would be met with economic sanctions by as much of the European Union as we can line up.

 There is a natural trade to be made between Canada and Europe. Maintaining a Canadian presence in Latvia and a Canadian mission at NATO helps to keep the alliance going.  It is still a North Atlantic Treaty Organization as long as there is at least one North American member.  The Europeans are already finding challenges in finding a replacement, perhaps predictably so.  Ireland’s neutrality seems to be getting in the way of turning the European Union’s security efforts into a European military.  So, the best shot Europe will have at a unified military effort is through the old machinery at Brussels and the various NATO sub-headquarters throughout the continent.  International relations scholarship asserts that it is far easier to adapt old institutions than develop new ones, which means building on the broken foundations of NATO than creating a new organization.  Canada, as a founding member, gives any post-US NATO legitimacy and a way out for European leaders who are frustrated with efforts to build an EU security organization.

As some have told the Europeans, Canada is the canary in the coal mine.  If Trump engages in a trade war with Canada, Europe is surely next.  Right now, Europe is defending its security by supporting Ukraine.  We need to convince the Europeans that supporting Canada now in these trade wars is the equivalent—better to support Canada’s trade fight now than to have to fight the US directly.

 We are still stuck in the transition as many actors are not quite willing to publicly hedge against the United States.  However, the effort by Trump to push Ukrainian President Zelensky into an awful deal—submit to the Russians and give up 50% of the country’s mineral rights—is teaching European leaders that playing the pandering, transactional strategy to survive Trump 2.0 will not work.  It is time to figure out how to realign our international institutions without the Untted States, it is time for Canada to find like-minded countries to come together to support each other in the fight ahead.  These past few weeks should make it clear to all that the break with the US is coming and coming quickly.

 So, the words of an American founder, Benjamin Franklin, apply now: “We must, indeed, all hang together or, most assuredly, we shall all hang separately.”

Serious Sweden

 I have spent the past week in Sweden as part of the Phil/Steve/Ora project seeking to understand the dynamics between defense agencies (departments/ministries of defense) and militaries in democracies around the world.  I was here in Stockholm last summer for the ERGOMAS meeting, but this trip was more like my visit to Finland last April.  One big difference, besides the weather being far more pleasant, was that I had a very well-wired reservist senior officer act as my fixer.  As a result, I met with a couple of former Ministers of Defence, a recent Supreme Commander (what they call their chief of defense), and several other high level current and former officials.  So, I got what I needed.

Another big difference is, well, the Trumpness of it all.  My fixer kept asking me to give a Canadian perspective on the state of things.  Most hadn't quite realized how serious Canadians are taking the 51st state craziness.  Once I put it into the context of how everyone around here lined up with Denmark over Trump's Greenland threats, they got it.  I did interview a Saab rep as he had previously been in defense, and I suggested that they might still have a chance to sell the Gripen to Canada as it will become very difficult politically for any Canadian leader to ship billions of dollars to the US to buy a plane when the US is increasingly becoming an adversary.

The Swedes understand that Article V of the NATO Treaty, an attack upon one is equal to an attack upon all, is either dead or in a coma while Trump is president.  They get it.  Some suggested that they need to invest more in bilateral ties since the multilateral effort may not work out so well.  

Sweden is serious about this stuff.  During my first day of interviewing, we were interrupted by a regular alarm--every Monday apparently--that, if any other time, would signal an attack (presumably Russian).  The Swedes had been cutting their military for decades and organized it around expeditionary operations (Balkans, Afghanistan, etc), and since 2014, the budget went the other way.  Sweden is now at 2.4% defense spending/gdp and is headed towards 3%.  They went from not having any planes flying on holidays to putting a regiment on Gotland.  They stopped conscription in 2010, and then restarted it, now with women being drafted as well as men.  It is not the full out conscription of the distant past--they only take 10% or so of each cohort.  The struggle is developing enough capacity to train more and more people.

There is much discussion of Total Defence--civil defence, mobilization for war, and all that.  I have been asked by the Canadian media should we do the same.  I scoffed as (a) the old civil defence people are nostalgic about involved bomb shelters that would not shelter folks from nukes, (b) the Russian military threat to Canada is inflated.  The conversation has, of course, turned to civil defence against... US attacks. And again, I am not sure if the expense is worth it.  I am still pretty convinced that the conflict between Canada and US is political and economic and not military.  And I also think that Trump might risk munity (military refusing orders, not a coup) if he tries to use force against Canada.  I think shooting protestors and attacking Canada are far likely to get more resistance than, say, grabbing Panama.

One thing that did rub me a bit the wrong way--lots of references to World War II as if they had taken a side.....  Very strange.

Anyhow, I got a lot out of this week, including freaking out some Swedes about Trump.  I didn't do much tourism as I spent most days interviewing folks, and I had seen stuff last summer.  I did go to a couple of medival kind of restaurants because I needed some silliness.  

Back to Berlin for some interviews there plus a roundtable on whether militaries can help stop democratic backsliding. I am going to have to postpone my plans to do this research later this month in Poland--I don't have my act together.  So, I will probably travel in western Germany to interview a general and see a part of the country I haven't seen thus far.  Much more work to do on this project, and I am lucky that folks are willing to talk about this stuff.  More interesting conversations ahead.

 

Zo Much Skiing: Does It Materhorn?

Zermatt is a pretty small town, not a city.
The restaurants fill up. Far more crowds
here than on the lift lines.

 I am taking advantage of my three months in Europe by taking many forms of transportation to get to Zermatt, which has, yes, many forms of transportation to get one to the top of the various peaks: big gondola, small gondola, chair lifts of varying sizes, funiculars (can't spell it without fun), and a ski train.  

 This place is massive as it comes three different mountains with the weather-affected ability to ski over to Italy and Cervinia.  My ski days have not been that long as I get worn out pretty quickly, but wow, this place is amazing.  Last year, I skied Zurs and Lech and related areas, and that seemed big and extensive.  This place has way more height and breadth--something like 50 lifts across the two countries.  

Mid mountain cafe/restaurant for
a much needed breather and
hot chocolate.

Like last year, they haven't gotten a ton of snow lately,
but there is more softer stuff here than last year at Zurs.  Still, lots of hardpack, some ice, which makes the steep stuff a bit more daunting, and invokes the old skills I learned in the mountains of Pennsylvania--how to use one's edges to ski on ice.  Over the course of the week, the conditions improved and I got better at avoiding the iciest areas, so I strained my legs less and lasted longer each day.

I was eager to get over to the Italian side on my first day because weather often interrupts that connection, and my basic skiing desire is to ski as much of a place as I can--a FOMO on skis, if you will.  I got to the gondola early--first one, and as I remarked to a bunch of Americans who were behind me, best to wait 30 minutes in the front of the line than 30 minutes in the back of the line.  It took about 40 minutes to get to the top, and required not just the gondola stopping several times at stops along the way, but another, much bigger gondola to get to the very top.  So high that the Materhorn was mostly next to rather than above us. 

The view of Italy from the top of Cervinia's slopes

Then I skied in Italy's direction--the pass I bought covers both sides.  One of my fears every first day anywhere is whether my pass has been processed ok or not, but I got through without a problem.  I then decided to go to the very end.  The village of Valtournenche is at the end of the longest run in the world apparently 22km.  And it felt like it--the skiing itself was not too challenging--all red runs (intermediate) with just a pretty steep icy bit to start the descent.  The signage was pretty good, although I wish I had gotten prescription inserts for my goggles so that I could see the numbers more clearly--each trail has a number that is posted, while the names are only on the maps.  It was a pretty bright, clear day as I kept going and going.  It took me about an hour, with many stops along the way to catch a breath and apologize to my thighs and my feet.  In many spots, I could get a good rhythm, in some I was mostly turning and sliding to avoid going too fast down a narrow traverse.  Again, not enough fresh snow in some parts. Once I got down, I then had to take a series of lifts--gondolas and chairs to get back up far enough that I could then ski to the other village--Cervinia.  My original intent for this trip was to stay there and then occasionally ski into Zermatt, as Cervinia has great intermediate runs and lot of them and lots of good food.  But I couldn't find an affordable place that was convenient to the slopes.

So many restaurants and cafes all over these mountains.  So, I stopped off at one near a lift on the Italian side and had a monster slice of pizza--it was thick and wide and pretty tasty.  I took my time as I was pretty tired.  When I ski Whistler or Lake Louise, I tend not to go top-to-bottom, usually just skiing part of the mountain.  So, two top-to-bottom runs took a lot out of me.  Just amazing views and some fun terrain along the way.  I then grabbed a series of lifts to get me back to Switzerland (I ended up paying an extra day of roaming since my phone was in Italy and Switzerland).  I then started skiing down the Matterhorn Glacier Paradise--well named as it is indeed a glacier and is a skier's paradise.  It was here where I made my only mistake--I ended up at the wrong lift, so I had to go up a small one (next to a nice slalom run that tempted me, but I was too tired--but I did that my last day, see below), and then took the gondola back to the bottom.  I was just too tired to ski out.   

Ski train at the top of Gornergrat,
a working observatory is at the peak

Wow, that was long.  Well, I will be faster about days 2-4.  Day two started with the ski train--yes, a train that exists to go up to the top of Gornegrat, which is the middle peak on the Zermatt side.   There were good runs that took me halfway down and then I wanted to check out the next peak over--Rothorn.  It was a long run, mostly fun, a bit of annoying narrow traverses.  But I was glad to do it, as Rothorn has some of the best cruisers.  Also, I found a great restaurant/bar along the way that had great hot chocolate and a sweet dog awaiting guests.  Skiing out at the end was fun.  The weather that day and the next closed the border with Italy (the lifts more than the border).  We didn't get as much snow as I had hoped.  

That night, I couldn't get into my first choice restaurant, so I went to a Swiss place.  The guys next to me were speaking English, and then when I heard "Trudeau," I realized they are Canadians. Turns out they are based in Manotick, the town next to my suburb, the one I go biking through for bice cream.  I kept bumping into these guys--once the third day on the furnicular and once on the fourth day at the gondola station on the Matterhorn glaciar.  Similar bumpings happened with a Canadian I met this morning who ended up at the same restaurant for lunch on the Italian side and with some young French women who were on the gondola this morning and then at the
same bar on the run out at the end of the day.  Zermatt is both big and small?  Oh, I bumped into the Americans who waited with me on day 1 at the gondola before it opened at a cafeteria in the middle of Gornergrat on day 2.

Day three was the reverse of day two--I started on Rothorn and then went to Gornergrat.  I just liked the runs at the top of Rothorm so much.  I explored more of the middle including finding a village I skied through.  I also found a restaurant that had its own trail to access it that had some great hot chocolate and a wonderful apricot strudel.  I always get apple, but the waitress said this was fresh out of the oven, and she earned her tip with that great advice.  My trip down Gornergrat was interrupted by a helicopter than landed on the trail right after I passed that spot. Not sure what happened there.  But the way down to the bottom after that was pretty sweet.  It was my first of two times going down the run out from the first gondola stop up the mountain past a bunch of bars.

The Matterhorn went from
brown to white due to
some fresh snow. 

 

 

 

 

 

My last day was a repeat of the first except I did more of the Swiss side before going over to the Italian side, and I didn't ski forever on the Italian side. I went with purpose--for a great Italian lunch under the Materhorn.  And I also got to try some trails on the right side of the mountain (as one looks down from the top), having done the left and the center on Monday.  I got lucky as the border is often closed due to weather.  It was closed Tuesday and Wednesday, but not Monday or Thursday.  Just provides so much more terrain, different light angles, and space.  For most of the four days, on most trails, I often felt alone.  Not as much this last day, but still plenty of times I didn't have to worry about traffic. I have become Thoreau-ian--choosing the path less traveled.

 

 

 

Random observations along the way:

• What is it with Sweet Caroline?  Last year at Lech, the gondola played it and folks sang along.  This week, on a couple of different gondolas, it was played, and people sang along.
• I mentioned above that the slopes were not that crowded (except when a huge gondola disgorges many people--then I just took pics and waited).  The mountains and the 50 plus lifts absorb a lot of people.  The worst liftline was about 20 minutes, and that happened once.  I rarely had to wait.  But the town of Zermatt is small, so walking into a restaurant and getting seated is a gamble.  I didn't make many reservations, and I ended up having to go with second choices.  Which worked out fine, meeting Canadians who live near me.  The restaurants on the slopes--very different--no problems there.  

  

  Last day, I induldged
  at one of the bars that
  line the runout.

• Oh, no need for passport to cross from Switzerland (a non-EU country) into Italy.  And, no, I didn't go through customs at the airport--Switzerland isn't in the EU but it is a Schengen country.  Makes all of this much easier.
• Strange to go skiing and not hear any Aussie accents.  I heard a lot of French, German, and Italian, and everyone could speak English, but no Aussie accented English.  
• The Trump stuff came up from time to time--no fans here.  Just Europeans marveling at how crazy things are.
• 
  People often say that American serving sizes are big, but I have to say I was most impressed with the sizes of the dishes I ordered, including this slice of pizza which was about two inches think and about the size of my head 
  
  
  
  

 Oh, and I finally grabbed the chance to do a race course--a short one--and it had automatic video!!!

 

 

Why Civ-Mil People Are Freaking Out?

 Trump bravely waited until Friday night to purge the top level of the US military.  Why are people freaking out?  We knew this was going to happen.  Trump promised this before the election, and the selection of Hegseth, a misogynist and racist, made it clear where we were heading   Yet now we are angry.  Well, not every Trump promise comes to pass although a lot of the worst ones do.  And reality just hits a lot harder.

So, for those who are not students of civil-military relations, why is this so bad?  First, a list and then a scenario or two.  And then what to expect soon.

1. The whole idea of having the top leadership of the military have terms that overlap with different presidencies is to avoid politicizing the military.  Never before has a President just erased the highest levels of the military a month into office.  Trump would have been able to change these folks within his four years--these people tend to serve 2 or 4 year terms.  So, why is he so impatient?  See some of the list below, but it might be that Trump wants to flex, show that he is a dictator right now.  Who purges militaries?  Autocrats.
2. Trump wants to prove to his base that his intent to re-segregrate the US includes the military.  All this anti-DEI stuff is really about being racist, misogynist, homophobic, and xenophobic.  No accident that they are replacing a Black man with a white one and getting rid of perhaps the most effective Chief of Naval Operations in a long time who just so happens to be a woman.  This move tells the force that only white straight men should lead.  That will be bad for recruitment and retention.  
   
3. Trump's replacement, Dan Caine, is a retired white dude.  This is not unprecedented as Kennedy had brought Max Taylor out of retirement.  Did that go well?  Um, Cuban Missile crisis good, Vietnam bad. But importantly, it was not aimed to make the military more loyal to Kennedy or the Democrats.  It might have been aimed to assert civilian control of the military.  What makes Caine better than all of the active generals and admirals?  That he is loyal to Trump, the person, and not to the Constitution.
4. Everything the new chairman does will be seen as partisan, not just political, no matter what he does unless he pushes back against a Trump order.  So, even relatively ordinary stuff will be tainted.
   
5. Trump also fired the Judge Advocate Generals--the lawyers.  Why fire the lawyers?  They tend to get in the way when you want to do illegal stuff.  So, Trump's intent is pretty clear.
6. This will divide the military.  Everyone will look around and ask themselves if someone is getting promoted because they are the best officer or because they are loyal, so political affiliation will be something everyone pays a whole lot more attention to. To be clear, there are at least three kinds of officers in the military: those loyal to the Constitution, those who are MAGA types who believe in this shit, and, most importantly, the careerists.  Those will do what it takes to get ahead, and have just been signaled that to get ahead, one has to do whatever Trump and Hegseth order.
7. Once you politicize the military, it becomes very hard to undo.  Let's say the GOP loses the 2028 election and leaves power peacefully (we can dream, right?).  The new President does what?  Fire all Trump appointees in the military?  That is pretty partisan--the replacements will be seen as lackeys to the Dems even if they are not.  Once the military is deeply into partisan politics, it simply will be hard to take it out of partisan politics
8.  What does Trump want to do with a more partisan, more personally loyal military?  Well, the last time Trump was in power, he wanted to use the military against peaceful protestors, and he faced some friction from the SecDef and Chairman.  Hegseth certainly is not going to get in the way, and neither will the puppet Trump just picked.
   

Ok, this does not mean that American troops will be gunning down protestors tomorrow.  First, Trump has to change who is the head of Northern Command, since that is the officer who orders troops in the US to act.  The chairman just advises the president--operational command runs from the President to the SecDef to the regional commander.   Second, they will need a pretext, but pretexts are like streetcars--there will be one coming down the road every five minutes.  With massive deportation, with the Musking of government, with everything going on, there will be protests.  Third, Trump will need loyalty all the way down.  The generals can order the troops to shoot, but the captains and lieutenants may not follow through.  The sergeants and the corporals may not follow through.  People will point to Kent State, but that was an accident.  And it stopped quickly.  It was not a situation where the troops were ordered to shoot and kept shooting.  

The thing is: if Trump orders the troops to fire and they don't, the military is disobedient and won't be trusted.  That's not great in the long term--to have a military that is contesting policy.  If Trump orders the troops to fire and they do shoot at civilians, well, that too is bad for the military and for political order as then the military is a tool of repression.  And if some troops fire and others do not, then you get a military that falls apart.  

One more scenario to fill your day with sunshine.  We are seeing states differ in how they will enforce Trump's dictats as well as their own laws. Texas wants to have abortionists in NY extradited, and NY is refusing.  Soon, you will see some states blocking massive deportation.  What happens next?  One might see the Texas governor send troops to NY or California to get the people they are seeking, and then the governors of NY or California call out their national guard to resist, and these NG's resist being federalized.  So, Trump then calls out the army to repress the dissident national guard....and that's how a civil war starts.  Either by the army fighting the California National Guard or by the army fighting itself as factions within the military take opposing sides.

Sounds like fantasy, doesn't it?  It all has become far more realistic than ever should have gotten.  Last night was the worst night in US civil-military relations since the Civil War.... but as the Simpsons cartoon would suggest 

   What happens next?  The Democratic Senators make a fuss during the confirmation hearings of the replacements.  Don't expect the GOP to raise that much of a fuss.  They confirmed Hegseth, they confirmed Patel even though he clearly perjured himself during the hearings.  Expect Trump to keep on firing generals and admirals, especially those commanding forces in the US.  Expect agent selection/moral hazard to kick in: he may promote some generals and admirals who then stick to their oaths and refuse to follow illegal orders and may refuse to implement awful but lawful orders.  Expect Trump to find compliant generals and admirals who then issue orders that are followed but not as completely or as quickly or as with as much cohesion and unity as in the past.  

Politicization of the military, bringing the military into politics and bringing politics in to the military is bad for military effectiveness, it is bad for democracy, and we are now here, deep in the middle of it.  And getting out is going to be really hard and will do lasting damage.

Among the many tragedies is that it didn't have to be this way.

A Strange Brave New World: The International Relations of Captain America

 I went to see the new Captain America movie last night in Berlin.  It is the Berlin movie festival, but, nope, this movie was not part of it.  The last Marvel movie that had this much international relations was probably Captain America: Civil War [unless one counts Black Panther 2 which had some truly dumb alliance politics] since the focus was on the UN facilitating the Sokovia Accords (another genius move by Thaddeus Ross), so I wanted to apply a bit of ye olde IR analysis to it.

 Before I get to it, just a few notes on seeing the movie here:

• 3D glasses are a Euro, and I had to ask people to find out where they were--not intuitive at all.
• the audience was super patient--even more ads than in a North American theater (including one for Bundeswehr recruitment!),  AND it was a lot of credits to get to the post-credit stinger, which was meh.
• they apparently don't clean between screenings and the previous folks were messy.   

Applying my 30 plus years of IR scholarship after the break so that I don't spoil the movie:

More Unforced Errors, NATO Edition

The only really surprising things about Trump 2.0 has been its pace and the Musk of it all.  But resegregation efforts at home (the anti-DEI stuff) and selling out Gaza were quite predictable.  Alas, so too is the destruction of NATO and the abandonment of Ukraine.  Let me focus on NATO since, yes, I co-wrote a book on it that may no longer be relevant (still my fave book).

Super unqualified and disqualified SecDef Hegseth made it clear to all at his first international meeting:

 To be as clear as I can be, there is no stark strategic reality preventing the US from being the primary guarantor of security in Europe.  Sure, the days of US national strategy documents aiming for the US to be able to fight two large conventional wars and do other stuff as well are long gone.  But guaranteeing European security does not require the ability to fight Russia and China at the same time.  It requires the ability to deter both, and that is something quite a bit different.

Going in the wayback machine, for much of the Cold War, especially the 1970s and 1980s, the US's commitment was not to defeat a Soviet invasion (only Tom Clancy's fiction suggested this), but rather that the presence of large numbers of American troops would commit the US to being at war immediately, and that possibility of that war escalating to a nuclear exchange would be sufficient to deter the Soviets.  

And it worked, as far as we can tell--I haven't looked at the Soviet archives or read post-Cold War stuff on this, but we have more recent evidence: that Putin has not engaged in any conventional attacks on NATO countries despite the flow of heaps of arms into Ukraine.  The US strategy has always been to interdict the flow of arms into the conflict zone--that is what bombing and invading Cambodia and Laos were all about.  But Putin has been restrained--that any conventional attack on a NATO ally would quite likely lead to an American response that might then lead to a process that ultimately could get out of control.  

The strategic reality that changed yesterday was not that the US can't do this anymore (indeed, defense spending is going to go up).  No, the strategic reality that changed is that the US is now led by a guy who wants to be a dictator and is far more comfy hanging out with autocrats than being in a club of democrats.  It is a matter of will not, not cannot.  And, yes, this was predictable--I made a bet last year with someone (I forget who) that NATO would not survive Trump 2.0.

Sure, the Europeans should spend more on defense, but the ironic key to collective security was depending on a single actor's credibility, the US, and not really on a collection of countries with their own convoluted dynamics.  NATO credibility/deterrence was based on a single player.  Can Europe provide a similarly convincing deterrent?  As to misquote Kissinger, who picks up the phone when you call Europe?  The statement that came out yesterday was good, but can the Baltics and the Finns and the Poles count on the resolve not just of Germany or France or the UK but on their remaining simultaneously and continuously resolved?   Oh my.  

While Hegseth is making my 3 months in Europe this winter/spring more interesting, I'd rather it not be so.  None of this was necessary.  I keep saying it didn't have to be this way.  So, one element of the tragedy of all of this is that it is entirely optional, despite what Hegseth claimed.  Indeed, the one thing this thing demonstrates is that a government of Bad Faith cannot be a good ally.

 

 

 

 

 

 

Outlandish? Hell Yeah

 I saw this and got a bit miffed:

https://www.researchgate.net/figure/
A-map-of-the-historical-territorial-expansion-
of-the-United-States-of-America-
Source_fig1_330787808

This economist is a crappy social scientist.  Yes, the US started with 13 states and is now at 50, so it is not outlandish that it could grow further, adding new states.  Indeed, I have been advocating statehood for the District of Columbia and for Puerto Rico (if the folks there want to do so).  But the context here is, of course, Canada.  I have already discussed the Trump 51st state bullshit, but since economists are spouting dumb things,* it is my duty as a political scientist to remind them that politics is a thing.

First, a quick dance through history and how the US got from 13 to 50 states:

• A good many states came from the original territory the US got as a result of the Revolutionary War--the way west to Wisconsin, Illinois, Tennessee and Mississippi.
  
• Jefferson violated his own principles because the amazing opportunity to buy the Louisana Territory appeared, so the US bought that vast tract of land from France.   This would be the best Greenland analog if not for the fact that Denmark ain't selling or ceding.
  
• The US got an even better deal when Spain wanted to get out of Florida (a pretty smart move).
• Texas.... is a complicated story leading to Six Flags parks (ewwww, I just learned what the sixth flag is).  Settled by Americans, first they tried to be independent, seizing land from Mexico, and then the US defended Texas from Mexico and got most of Texas and some chunks of a few other states as well.  
• Shortly there after, the US-Mexican war led to the US getting much of Mexico--the southwest US as we know today (if Utah and Nevada count as southwest).
  
• Another good deal--US bought Alaska from Russia.
• And then the conquest of Hawaii
  

So, much of this was European settlers giving up their claims to the US.  Is the UK going to give up Canada to the US?  Nope, it can't thanks to the UK giving up its claim to Canada (a Canadian historian can tell you better when this happened, but I believe it happened several times).

Of the cases above, the closest that comes to a pre-existing independent country was Texas.  They sought/agreed to annexation because of fear of Mexico if I remember correctly.  Is Canada so scared of Russia that it would rather give up independence?  Um, no.

So, the other model is conquest a la the southwest or Hawaii.  Yes, the US military would defeat the Canadian military in days .... if the US military followed orders to attack Canada. But controlling Canada would be hard--while much of the huge country could be ignored, controlling the cities along the border and, yes, the pipelines, would be tricky.

One of the things that is widely ignored is that most states became states only after having referenda or ratification of the state constitution (Check out this handy guide).  How would such a ratification vote go these days in Canada?  It would fail miserably as most Canadians reject the idea.

What Trump and the economist get wrong is that countries have their own domestic politics.  Being annexed by Trump's US is wildly unpopular in Canada and in Greenland.  Politicians contemplating such a merger would be risking their own careers in a big, big way.  No Canadian politician is going to advocate for merger--not if they want to have a political career in Canada.  Plus it would involve federal-provincial politics and Canada-Indigenous People politics.  Good luck sorting that out.

Oh, and the only way to make it at all imaginable is to turn Canada not into the 51st state but into states 51st-60th (or more).  No way Quebec is going to lose everything it has demanded over the years to join the US.  While one state might upset the balance of things a smidge in the electoral college (if there are ever free and fair elections again), adding 7-8 likely Democratic states is something no Republican would go along with.  

Oh, and, yes, the norms of conquest and selling territories inhabited by people have changed over the years, so the international context is very different.

So, all this 51st state is beyond outlandish.  It is ridiculous, but it will live on because Trump likes to troll people and because ideas enter his depraved, demented skull and then get stuck and mutate.

* To be fair, any person working for Trump is going to be asked to justify the most batshit, the most cruel, the most self-destructive policies, so they are usually quite desperate and have only weak responses.  Of course, no one is forced to work for Trump, so the fact that they are stuck in a crappy position is entirely on them.  My new slogan for Trump 2.0 is "Empathy for Everyone Except Trumpers"