Is anyone surprised? On the last day of 2019, after months of threatening the United States to ease its nuclear standoff with “a bold decision” by year’s end — or else — the leader of North Korea darkly announced that the country would unveil a new strategic weapon “in the near future.” Kim Jong-un also declared an end to a moratorium on nuclear weapons and missile tests. On the first day of 2020, he did not deliver his customary, often fiery, New Year’s address. In other words, he interrupted his regularly scheduled program to bring us his latest threat.

The false calm is over; the old North Korean nuclear crisis is back on — only, it has just entered a deadly serious phase. The government in Pyongyang is looking to establish a new normal: One where it gets to threaten San Francisco with incineration, and we get to do nothing. The United States’ only option for precluding this nightmare is to bring down the hammer on the Kim regime before its capabilities expand even further.

As usual, North Korea is setting the scene and the tempo for the dance of death now unfolding. Mr. Kim has just personally decreed an end to the season of diplomacy — after personally summoning it into existence at the start of 2018.

In his New Year’s address that year, he publicly declared that the North Korean arms industry “should mass-produce nuclear warheads and ballistic missiles” — the power and reliability of which had been well established, he also said. In the perverse logic of North Korean signaling and gamesmanship, this actually was an indirect overture: a suggestion that Mr. Kim might now agree to an invitation that he halt tests of both nuclear weapons and intercontinental ballistic missiles (ICBMs). It was also a hint that he might be willing to enter into talks with the United States and South Korea.