I don't think McCain had any objections about going into Iraq. And foreign adventurism comes in many forms. I would argue anything outside of a relatively isolationist stance is adventurism, and invites a assymetrical attacks from abroad. To me it is blindingly obvious that the containment of Iraq and the 9/11 attacks and other al Qaeda attacks were related in that if we were not participating in the containment we would not have put ourselves in the position to become a terrorist target. As long as we have lost more people due to containment than in actually fighting and removing Saddam, the Iraq war will definitely be worth the cost in my book. I sometimes think the Bush administration should have put forth this argument, but then you would have to deal with the counterargument that the US "deserved" 9/11 due to its foreign policy.

McCain has struck me, since the 2000 campaign at least, as a grandstander who does what he thinks will give him favorable press attention--especially if it'll make the party squirm. The idiotic McCain-Feingold law is the most feckless such example.