A few hours before Donald Trump’s first State of the Union speech on Tuesday evening, the news broke that the White House was scrapping its choice for ambassador to South Korea, a position that remains unfilled a year into the administration.

According to The Washington Post, the nomination of Victor D. Cha, a hawkish veteran of the George W. Bush administration, was very close to being sent to the Senate, but was derailed when Cha privately expressed reservations about a preventive American strike on North Korea. The Financial Times reported that Cha was asked if he was “prepared to help manage the evacuation of American citizens from South Korea,” which would be necessary in the event of an American bombing. This is terrifying, because it suggests that Trump is serious about starting a war.

Indeed, Cha himself seems frightened; just before the State of the Union started, he published an op-ed in The Washington Post arguing against a preventive attack. Apparently assuming that some readers would be indifferent to millions of potential Korean deaths, Cha emphasized that many Americans would also die in a military confrontation. “To be clear: The president would be putting at risk an American population the size of a medium-size U.S. city — Pittsburgh, say, or Cincinnati — on the assumption that a crazy and undeterrable dictator will be rationally cowed by a demonstration of U.S. kinetic power,” he wrote.

Cha’s warning made Trump’s State of the Union bellicosity toward North Korea particularly frightening. More than an hour into an interminable speech, Trump said, “North Korea’s reckless pursuit of nuclear missiles could very soon threaten our homeland.” He added: “Past experience has taught us that complacency and concessions only invite aggression and provocation. I will not repeat the mistakes of past administrations that got us into this very dangerous position.”