“We take for granted the degree of peace that we’ve enjoyed over the past eight plus decades. And we think that’s the norm. The norm is actually a lot more like what the world looked like before 1945. Certainly, the previous 100 years were one of constant great power warfare. And I don’t think people are ready for that—the world that we’re now moving into.”

As the distinguished historian Robert Kagan puts it in this provocative Conversation, Trump’s foreign policy may be a decisive break from the past that will not be followed by a return to the status quo. According to Kagan, we are at risk of returning to a multipolar world of shifting alliance structures and transactional foreign policy that would greatly endanger American security. Kagan’s bracing account considers the stakes of current foreign policy challenges in Asia, the Middle East, Latin America, and Europe—as well as the contest over liberal democracy at home.