President Trump greets U.S. military commanders in South Korea.Jonathan Ernst / Reuters

Just hours before Donald Trump pledged in his State of the Union address to counter the nuclear threat from North Korea with “maximum pressure” and “American resolve,” the man who was once poised to be the U.S. envoy to South Korea issued a dire warning about what might be behind the president’s words.

For weeks now, speculation has swirled that the Trump administration is seriously thinking about conducting limited military strikes against North Korea to give Kim Jong Un a “bloody nose”—with the aim of deterring him from further developing a nuclear arsenal that could soon threaten the U.S. mainland. South Korea’s president claimed that Trump had denied such plans in a private phone call, but publicly Trump and his advisers haven’t commented on the reports. Writing in The Washington Post on Tuesday night, shortly after news broke that he was no longer under consideration to be ambassador to South Korea, Victor Cha suggested that the “bloody nose” option is real—so real, in fact, that his opposition to it might be the reason he won’t be heading to Seoul.

Some officials in the Trump administration believe that a circumscribed use of force “would shock Pyongyang into appreciating U.S. strength, after years of inaction, and force the regime to the denuclearization negotiating table,” wrote Cha, a prominent Korea scholar and former official in the George W. Bush administration. They also believe that the United States could keep the conflict from spiraling out of control and exacting massive human and economic costs even if North Korea retaliates. He pointed to the difficulty of evacuating American non-combatants from South Korea and Japan—not ahead of a strike, but “under a rain of North Korean artillery and missiles (potentially laced with biochemical weapons).” The implication seemed to be that Trump is mulling a surprise attack.

Cha rebutted the argument that it was better to fight North Korea in Asia than to allow it to get a capability—one it might never use—to target the United States with nuclear weapons:

While our population in Japan might be protected by U.S. missile defenses, the U.S. population in South Korea, let alone millions of South Koreans, has no similar active defenses against a barrage of North Korean artillery (aside from counterfire artillery). 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.

Cha is no dove on North Korea. He echoed H.R. McMaster, Trump’s hawkish national-security adviser, in arguing that failing to prevent North Korea from becoming a nuclear-weapons power would present the United States with a range of awful new threats: Kim Jong Un could use his nuclear missiles to blackmail America into abandoning its South Korean ally, sell nuclear weapons to other countries or terrorist groups, and inspire U.S. adversaries to acquire their own nuclear weapons or otherwise challenge the United States. But the “preventive military strike” under review by the Trump administration could escalate “into a war that would likely kill tens, if not hundreds, of thousands of Americans” and potentially even “a nuclear war,” Cha wrote. He maintained that the administration’s military plans are premised on “hope” rather than sound reasoning—and that there are less perilous ways to deter North Korea from using its nuclear weapons and proliferating nuclear technology while preparing military responses should deterrence fail.

When I spoke with Cha last spring, he told me that there were really only two options at this point for dealing with the North Korean nuclear program. The first, which he favored and which the Trump administration is currently pursuing, was to impose severe international sanctions on the Kim regime and pressure China into fully cutting off its economic relations with North Korea. The “diplomatic answer is that that would then be a segue to negotiations in which everybody would be united [on] the terms for North Korea to freeze and then dismantle their program,” explained Cha, who in the past has expressed doubts that the current North Korean government will give up its nuclear weapons. “The undiplomatic answer is that it puts enough pressure on the regime that there will be some sort of internal problems, and that Kim Jong Un might be challenged by others who see a better path for North Korea.”

The second option was military action, Cha said, but there’s a good reason that every president since Bill Clinton has deliberated over striking North Korea’s nuclear sites and ultimately decided against it. Since the various components of the North’s nuclear program are spread out across the country, and in many cases are mobile or nestled underground or undersea, a U.S. bombing campaign would at best set back the program several years rather than destroy it, he noted. And North Korea’s tremendous capacity to retaliate against the South Korean capital of Seoul or U.S. military bases in South Korea and Japan with artillery, ballistic missiles, and weapons of mass destruction means that a conflict on the Korean peninsula could result in “millions of casualties.”

“It’s certainly true that dictatorships like North Korea—their primary goal is to survive,” Cha told me. “So could you carry out a strike against their nuclear facilities with a threat that if they retaliate we will wipe out the regime? Will a rational dictator then sort of sit still? Possibly. But that’s a big risk to take.”

In taking the extraordinary step Tuesday of disclosing the disagreements that may have disqualified him from serving in the Trump administration, Cha signaled that the president might be willing to assume that big risk even though his predecessors all deemed it intolerable. Trump himself had something to say about his predecessors last night: “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.”

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