Before everyone becomes concerned about my sources, yes, I am aware that I am quoting an article from the World Socialist Web Site, which is "Published by the International Committee of the Fourth International (ICFI)."  However, I've run across stuff from these guys repeatedly on Twitter, and though I severely disagree with their economic plans, they seem to be pretty committed to principled opposition to war. 

Today there's a great article on Obama's continuation of the aggression of his predecessor, dubbed an expression of the "Obama Doctrine":

The Obama doctrine incorporates all of the essentials of the Bush doctrine—preemptive war and the assertion of the right of the United States, as the world’s “sole military superpower,” to launch military aggression unilaterally as it sees fit. Obama’s contribution is to argue openly for the junking of existing international rules of war and the recognition of what was previously defined as aggressive war as a legitimate instrument of foreign policy....

“Peace requires responsibility,” said Obama. “Peace requires sacrifice.” In short, peace requires war, whether those forced to die and to pay for it like it or not.

Read the rest of this analysis here.  Though the final paragraph ends with a call for opposition to capitalism, the persistent holding of Obama's feet to the fire where public opinion, his campaign promises, and even basic honesty are concerned make this well worth the read.