Last year around this time, North Korea tapped the world on the shoulder with an underground nuclear test that drew the usual international diplomatic tut-tutting.

This year, an encore: Kim Jong Un announced his country is preparing its first test of an intercontinental ballistic missile. Such a missile could reach the U.S. mainland.

In response, President-elect Donald Trump tweeted: “North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won’t happen!”

The North Koreans have long demanded one-on-one talks with the U.S. But they’ve also violated every agreement they’ve made with American presidents, including Bill Clinton and George W. Bush. Moreover, Kim views his nuclear program as his hole-card for his regime to survive. He won’t surrender it.

“As long as Kim Jong Un is in power, North Korea will never give up its nuclear weapons, even if it’s offered $1 trillion or $10 trillion in rewards,” says Thae Yong Ho, a former top North Korean diplomat who defected to the West last year.

It’s not about economic incentives, Thae says. Instead, North Korea seeks to be recognized by the U.S. and the West as a nuclear power.

Even without recognition, North Korea already is a de facto nuclear power. What can Trump do? He could try to negotiate a nuclear deal to slow or freeze North Korea’s program, as the U.S. did with the (admittedly imperfect) Iran deal. But he also should know that Kim can’t be trusted any more than previous leaders who violated past deals.

Trump can also deliver a warning: If U.S. intelligence concludes that North Korea is shopping its nukes or technology to terrorists or other nations, America will strike North Korean nuclear facilities. That’s a clear line in the sand that Obama couldn’t deliver convincingly.

The U.S. strategy of waiting out Kim and hoping to coax him back to the negotiating table — a stance the Obama administration dubbed “strategic patience” — has yielded a growing North Korean nuclear arsenal. Trump needs a new approach. He can start with a single premise: Allowing North Korea to build its arsenal, to spread nuclear technology and weapons, won’t happen on his watch. How he does that is negotiable.