And it’s coming. Iran and its proxies, having started one war in Israel, don’t appear reluctant to consider another with the U.S. A Russian victory in Ukraine, even a partial one, would make eventual confrontation with the North Atlantic Treaty Organization almost inevitable. China menaces Taiwan. And the possibility that Kim Jong Un isn’t plotting an attack on South Korea—or on the U.S.—is a bet only a fool would take.

These admittedly rather basic reflections occurred to me as I read Mark Helprin’s latest novel, “The Oceans and the Stars.” The book, which went on sale on Oct. 3, relates fictional circumstances that became far easier to credit four days later. Mr. Helprin’s novel imagines a war launched by Iran against the U.S. and Israel, a political class that views national security exclusively as a means of gaining electoral advantage, a perpetually irritable American president whose chief goal is to avoid blame, and an army of terrorists capable of savagery so repellent that Western elites refuse to contemplate it.