The key to the Saideman and Auerswald project on NATO and Afghanistan is that countries always can veto their participation in any operation. How did we begin to appreciate this? While studying Kosovo, we found that a British General (Michael Jackson!) said no to SACEUR (Gen. Wesley Clark, demonstrating the bad judgment that helped to make him incredibly unpopular within the US military) when he asked the Brits to outrace the Russians to the Pristina airport in June 1999. This risked a military confrontation, which the singer James Blunt refused to do. He and Jackson played the red card, saying no to Clark.
The questions for us are under what conditions to countries say no and who gets to the make that call? We didn't expect it to be a pop musician, but, hey, this project keeps getting more and more interesting and we cannot complain about that.