The North is correct that Seoul depends on the United States, but this is not flunkyism so much as an involuntary alignment with Trumpian aims. The American president is goading our Asian allies toward war, or something just short of it. His combat with North Korea has cast a defensive gloom over the region and given nationalisms a chance to flourish. Yet the more Japan and South Korea assert themselves, the less liberated they become.

In Tokyo, Trump gave Prime Minister Shinzo Abe fodder for his agenda of militarization and encouraged him to buy more weapons from the United States. Just outside Seoul, Trump went with President Moon to greet soldiers at Camp Humphreys and bragged that Korea would be spending “billions of dollars” on American-made armaments. Still, the administration demands “gratitude.” During and immediately after the Korean War, Seoul had no choice but to pursue a strategy of sadaesasang. The world was cleaved in two, and so the Korean Peninsula went — the South to the Americans; the North to the Soviets. Seventy years later, there are still more than a dozen U.S. military bases in South Korea, staffed by nearly 30,000 troops. This is not Trump’s doing, but his cavalier provocations have cemented Korean reliance on America.

President Moon, a human rights lawyer by trade, assumed office in May. He ran on a platform of left-of-center nationalism — political accountability, economic justice, denuclearization and improved relations with the North — after his right-wing predecessor, Park Geun-hye, was thrown out by a protest movement on the scale of the Arab Spring. But North Korea’s missile tests and Trump’s Twitter-enabled temper dragged him swiftly rightward. By early September, he was warning the North of “countermeasures” and allowed the United States to install the Thaad missile-defense system on Korean soil — a move that managed to anger both his supporters and the Chinese government.

A few weeks later, Moon tried to regroup in his speech before the United Nations General Assembly. He called for peace and situated himself, and the continuing nuclear standoff, in a lineage of war and division. “I was born in a refugee town in the middle of the Korean War,” he said. “I come from one of the separated families.” Yet the vast hall was mostly empty; only the Korean delegations and a man from El Salvador were in their seats. Though there is no state with more at stake when it comes to North Korea, South Korea is seldom heard.

The nuclear crisis is such that what passes for independent South Korean policy is this: the imminent construction of a Korean missile-defense system, wholly separate from the one already installed by the United States. (Never mind that it was purchased from Washington, or that Trump has veto power over Korean weapons payloads.) South Korea’s foreign minister, Kang Kyung-wha, took pains to explain this distinction in late October. “We will not participate in America’s missile-defense networks,” she said. “Thaad is a self-defense measure that has nothing to do with Korea’s missile defense.”