Chris Hayes makes it at the Nation. Not being a progressive in good standing myself, I can’t go along with everything he says, but this, for me, is key:

But while domestic policy will ultimately be determined through a complicated and fraught interplay with legislators, foreign policy is where the President’s agenda is implemented more or less unfettered. It’s here where distinctions in worldview matter most–and where Obama compares most favorably to Clinton. The war is the most obvious and powerful distinction between the two: Hillary Clinton voted for and supported the most disastrous American foreign policy decision since Vietnam, and Barack Obama (at a time when it was deeply courageous to do so) spoke out against it. In this campaign, their proposals are relatively similar, but in rhetoric and posture Clinton has played hawk to Obama’s dove, attacking from the right on everything from the use of first-strike nuclear weapons to negotiating with Iran’s president. Her hawkishness relative to Obama’s is mirrored in her circle of advisers. As my colleague Ari Berman has reported in these pages, it’s a circle dominated by people who believed and believe that waging pre-emptive war on Iraq was the right thing to do. Obama’s circle is made up overwhelmingly of people who thought the Iraq War was a mistake.