Trade accords had been a staple of the post-World War II world, providing a mechanism for economic growth, development, and association with friends and allies, and a means of reining in would-be adversaries who otherwise would have little incentive to act with restraint.

American presidents get to make lots of choices, with one critical exception: what awaits them in the in-box on top of the desk in the Oval Office.

Diplomacy can and will matter; little is inevitable in international relations.

Donald Trump's United States is not isolationist. He has authorized the use of limited military force against the Syrian government in a manner his predecessor rejected.