REPORTS THAT North Korea might be preparing a provocative test of a submarine-launched ballistic missile surely will not have surprised the seasoned foreign policy hands beginning to populate the Biden administration. The regime of Kim Jong Un, like that of his father, has a history of greeting new U.S. presidents with tests of nuclear warheads or long-range missiles. In the case of the Obama administration, the result was a deep freeze in relations; President Donald Trump’s response was threats of war, followed by failed summit meetings.

Kurt Campbell, a senior State Department official during the Obama administration who just became President Biden’s Asia coordinator at the National Security Council, warned last month about the need “to make an early decision about what to do about North Korea” to head off the predictable provocations. The problem is what to do. As Antony Blinken, Mr. Biden’s nominee for secretary of state, told the Senate Foreign Relations Committee this week, North Korea has “plagued administration after administration,” even as its arsenal of nuclear warheads and missiles — including intercontinental ballistic missiles that can reach the continental United States — has steadily grown.

That doesn’t seem likely to change anytime soon. At a rare conference of the ruling Communist Party this month, Mr. Kim said the development of its nuclear force had been “the exploit of the greatest significance in the history of the Korean nation” and promised a host of new weapons, including hypersonic missiles, nuclear submarines and ICBMs with multiple warheads. Some of those ambitions might be out of reach at a time when North Korea, having sealed its borders in an attempt to avoid the covid-19 pandemic, is suffering another severe economic crisis.

Yet the regime’s arsenal is already formidable. The U.S. Army reported last summer that North Korea might have 20 to 60 nuclear bombs and the capacity to produce a half-dozen more every year. While Mr. Trump’s showy but shallow attempts to engage Mr. Kim staved off further nuclear or intercontinental missile tests during the past three years, the stockpile of warheads never stopped growing.

Some North Korea experts say the strategy pursued unsuccessfully by the past four U.S. administrations — persuading the regime to denuclearize through a combination of economic pressure and negotiations — is no longer realistic. While Mr. Kim is willing to bargain with the United States, he aspires to do so only as the recognized leader of a nuclear power. In theory, such talks could result in partial reductions of Pyongyang’s weapons; some limits are better than none. But Mr. Kim’s price would likely be a weakening of the U.S. military alliance with South Korea — something that Mr. Trump was all too willing to consider and that Mr. Biden must reject.

Mr. Blinken told the Senate the new administration would “review the entire approach and policy toward North Korea” to “look at what options we have.” Yet as Mr. Campbell pointed out, the Obama administration’s “prolonged period of study” was punctuated by the regime’s provocative acts. Perhaps there is no way to avoid a showy missile firing or other martial demonstration by Mr. Kim in the coming weeks. If there is, the Biden team probably needs to come up with it fast.

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