But the brief era of internationalism sustained serious damage with the 9/11 attacks and has been tottering ever since. Yes, even under Obama, who ran for office proudly proclaiming his principled opposition to the Iraq War, charmed our allies, and tried to extricate us from international obligations in the Middle East, while simultaneously undertaking ill-considered military action with NATO in Libya. The Obama administration’s foreign policy was an incoherent mess, but the impulse to step back from international leadership was there from the beginning and remained a powerful motive until the very end.

Now Trump has reverted to the much more rabid anti-internationalism of the immediate post-9/11 period, but without any pretense of moral motives or effort at self-restraint. That’s the primary thing that distinguishes Trump’s America from Lyndon Johnson’s or George W. Bush’s America: We are now unbound and unconstrained, a military and economic behemoth acting like a free agent, doing whatever we please on the world stage.

There’s simply no way to know what will happen next.