I think one has to say it's not just simply a matter of capturing people and holding them accountable, but removing the sanctuaries, removing the support systems...
It would be a huge mistake to abandon democracy promotion. Peaceful political change has been enormously successful in the past years in Eastern European countries as well as in countries like South Korea, South Africa, Chile and Indonesia. However, if possible, the use of force is something to avoid except in cases where genocide is threatened, like Bosnia or Libya or with regimes that threaten our security, like the Taliban and Saddam Hussein.
The Western alliance should have supported the Sunni opposition against the Assad regime from the beginning. As far as Iraq is concerned, if it had stayed stable the way it was in 2008, IS would not have been able to expand in Iraq the way they did. The mistake was that Barack Obama withdrew the armed forces from Iraq too fast.