The success of Nato was not inevitable, easy or obvious. It is a remarkable and hard-won accomplishment, and one based on a recognition that the United States does not become stronger by weakening our allies. But that is just what Trump has done, repeatedly and deliberately.

He treats our partners as burdens while embracing autocrats from Moscow to Pyongyang. He has cast doubt on the US commitment to Nato at a moment when a resurgent Russia threatens our institutions and freedoms. He has blindsided our partners on the ground in Syria by ordering a precipitate and uncoordinated withdrawal. He has attempted to shake down South Korea and Japan, evidently mistaking our security alliances for protection rackets. And he has wrecked US credibility by unilaterally tearing up our international agreements on arms control, non-proliferation and climate change.