The rationale behind Donald Trump’s antagonistic posture toward our South Korean allies has never been clear, but whatever the reasoning, it’s getting worse and creating a more serious diplomatic challenge.

This year, Seoul will pay nearly $1 billion for the presence of more than 28,000 U.S. troops. Trump recently decided he wants $4.7 billion – a figure that reportedly “came out of thin air” – despite the advice of Pentagon officials who urged the White House to take a more responsible course.

This week, South Korean officials balked at Trump’s demands. As the Washington Post reported, it led an American delegation to walk away from the negotiating table.

The United States broke off talks with South Korea on Tuesday over how to share the cost of the two nations’ military alliance, injecting fresh tension into the relationship over Washington’s demands that Seoul pay sharply more. President Trump has demanded South Korea raise fivefold its contribution to cover the cost of stationing 28,500 U.S. troops in the country, asking for nearly $5 billion, officials on both sides said. But that demand has triggered anger from Korean lawmakers and sparked concerns that Trump may decide to reduce the U.S. troop presence in the Korean Peninsula if talks break down.

James DeHart, the top U.S. negotiator, complained that South Korean offers “were not responsive to our request for fair and equitable burden sharing.”

Or put another way, the United States is trying to shake down an ally as part of a scheme that resembles a protection racket. Our friends are uncomfortable with our demands, so we decided to stop talking to them until they agreed to pay us billions of dollars.

Oddly enough, while Trump’s policy toward South Korea is failing, his policy toward North Korea is failing in similar ways. The New York Times reported this week:

North Korea said on Tuesday that the United States’ decision to postpone a joint military drill with South Korea was not enough of an incentive for it to return to the negotiating table, and that it would not discuss denuclearization until Washington ended its “hostile policy.” On Sunday, the United States defense secretary, Mark T. Esper, and his South Korean counterpart, Jeong Kyeong-doo, together announced that the allies would postpone a joint air force drill scheduled for later this month. They described it as “an act of good will” aimed at bringing North Korea back to the negotiating table. But the North remained unsatisfied.

Pyongyang was glad to accept the canceled military exercises, but North Korean officials have told the White House that Trump and his team will have to up the ante if there’s going to be another round of talks – which, even if they occurred, would likely lead to more embarrassment for the Trump administration.

It’s not easy to fail with both countries on the Korean Peninsula simultaneously, but somehow, Trump has managed to find a way.