The abrupt resignation of U.S. Defense Secretary Jim Mattis has governments from Seoul to Brussels on edge, as the reliability of American alliances and the direction of policy under an erratic leader comes increasingly under question.
The former marine general was widely seen a moderating force against President Donald Trump's hostility toward traditional American alliances and overseas troop commitments, and had come to be described as "the last adult in the room.' Besides the immediate moves to pull forces from Afghanistan and Syria, Mattis's departure could have ramifications for U.S. standing around the world, from North Korea to Europe, where Trump's criticism of NATO has prompted calls to form a continental army.
Here's a look at how the change impacts some global tension points: