Kidnapping, torturing and murdering westerners - usually civilian contractors - isn't going to solve any of the problems that Iraq currently faces. It is pretty obvious that the governments of the nations whose civilians have been kidnapped will never back down to these demands, and rightly so.

The fact is, if they want troops to withdraw then they're making the situation worse. Their demands can't be met, otherwise terrorist groups would be kidnapping westerners left, right and centre in order to get their way. Not to mention that the governments are much more likely to withdraw their troops when Iraq is stable, ie when trouble, such as kidnapping, has stopped happening, although it is unlikely to happen any time in the near future.