Note that I did not say “defend Ukraine.” Our concern for others does not lead to unlimited military obligations. No nation, not even one as strong as ours, could bear that cost.

But this moment should cast our existing obligations in a different light, reaffirming their immense value. In fact, it is our understanding of the value of our national home—and the deeply destabilizing and violent pain of the loss of others’ national homes—that leads to the network of defensive alliances that has maintained great power peace for so long.

NATO is not “American imperialism.” Our defensive alliances in Asia aren’t the result of “imperial overreach.” To continue the comparison to home, a defensive alliance is akin to a neighborhood watch, where neighbors look after and protect each other. It is to our nation’s credit that we did not turn decisively inward after World War II, that we did not repeat the mistakes of the past and left our friends and allies to fend for themselves.