But as North Korea’s nuclear program has rapidly advanced, and as the Trump administration has sounded the alarms about that progress, such talk is creeping back into public discourse in Washington and beyond. The president and his advisers have avoided explicit discussion of nuclear war. Yet they’ve spoken increasingly openly—and with remarkable stoicism—about the potentially catastrophic toll of a U.S.-North Korean conflict, not only because both countries possess nuclear weapons but because North Korea has formidable non-nuclear arms and shares a heavily militarized peninsula with South Korea.

At the October conference, which was organized by the Foundation for Defense of Democracies, CIA chief Mike Pompeo noted that North Korea may be just months away from developing the capacity to place a nuclear warhead on a long-range missile that can reach the United States. The North Koreans are so close, in fact, that U.S. policymakers should “behave as if we are on the cusp of them achieving that objective,” he said. As for what behavior he had in mind, Pompeo stressed that Trump would rather use peaceful tactics—economic sanctions, diplomatic pressure—to deny North Korea this capability. But the president is determined to keep Kim Jong Un from holding America hostage with nukes, he added, even if that requires taking military action against the North Korean leader.

Next, National-Security Adviser H.R. McMaster spoke to the relative probability of peace and war, and the timeline in which one could give way to the other. It is “unacceptable” to “accept and deter” a North Korean government that can threaten the United States with nuclear weapons, he said, even though America has for decades successfully deterred Russian and Chinese governments that can threaten the United States with nuclear weapons. He stated that the Trump administration would only enter into negotiations if North Korea agreed to take initial steps toward dismantling its nuclear-weapons arsenal, even though North Korean officials claim this precondition is a non-starter.

In banking on a long-shot diplomatic outcome and refusing to tolerate any lesser result, McMaster was hinting that military conflict is a distinct possibility—and not a distant one. He did more than drop hints. “We are in a race to resolve this short of military action,” McMaster acknowledged. As one U.S. official told NBC News, in reference to why U.S.-North Korean diplomatic channels are breaking down, the Trump administration’s message to North Korea appears to be “‘surrender without a fight or surrender with a fight.’”

Trump, for his part, has threatened to “totally destroy” North Korea with a show of force that “this world has never seen before” in order to protect America or its allies. U.S. military action against North Korea isn’t “unimaginable,” Joseph Dunford, the chairman of the Joint Chiefs of Staff, argued earlier this year, even though “anyone who has been alive since World War II has never seen the loss of life that could occur if there’s a conflict on the Korean peninsula.” What’s unimaginable, he continued “is allowing a capability that would allow a nuclear weapon to land in Denver, Colorado.”