By Josh Lederman, Associated Press

Just when President Donald Trump’s strategy for North Korea was finally starting to show dividends, he threw it a curve.

At long last, his administration seemed to be speaking with one voice on a key national security issue, a surprisingly elusive task in Trump’s first six months. But he upended all that with a threat to slam the North with “fire and fury like the world has never seen” if it provoked America again.

By inflaming the situation, Trump also may have undermined the only serious prospect for resolving the North Korea crisis: successful cooperation with China.

Trump’s strategy has relied on a delicate diplomatic two-step: increasing pressure on China in hopes that, in turn, China will use its influence to get North Korea to abandon its nuclear aspirations. Trump had been deeply frustrated by China’s recalcitrance, but there were signs it was finally coming around, including its vote in favor of the toughest U.N. sanctions in a generation — possibly ever.

On its face, Trump’s move seemed to fit a pattern in which he becomes his own biggest obstacle to achieving his objectives. Sometimes he exposes divisions within his administration that others can then exploit. Other times, Trump stakes out positions so unpopular that needed partners can’t afford to work with him. In other cases, he’s played directly into his critics’ worst suspicions about him.

That tendency has been on display repeatedly, including in his firing of the former FBI director who had been investigating his campaign’s possible Russia collusion, his “Muslim ban” comments that sank his travel ban in court, and siding with Saudi Arabia over Qatar in the Persian Gulf crisis just as his administration was trying to mediate.

With North Korea, it was the budding prospect for the cooperation he’d been seeking from Beijing that was jeopardized by his latest unforeseen move.

In recent months, Trump had been so frustrated by Beijing’s reluctance to help that he let it be known he was considering new, punitive trade actions. The Treasury Department had even prepared unprecedented “secondary sanctions” targeting Chinese companies and banks that deal with North Korea.

But Trump agreed to hold off after China, with its U.N. Security Council vote, signaled it was finally moving in the direction Trump wanted, U.S. officials said.

So when Trump seemed late Tuesday to lower himself to Kim Jong Un’s level, aggressively threatening the North with physical force, it wasn’t just Washington that was taken aback.

“For the leader of the most powerful country in the world to be talking about the ability to annihilate another country with a power never seen before not only gets a reaction from Pyongyang, but from Beijing, and Europe,” said Jeffrey Bader, formerly President Barack Obama’s top Asia hand who now runs the Brooking Institution’s China program. “That is not helpful to our interests.”