A U.S. soldier stands guard in front of the Peace House, the venue of third inter-Korean summit in Panmunjom, South Korea, on April 18, 2018. Photo: Chung Sung-Jun/Getty Images

For years President Trump has expressed his desire to withdraw U.S. troops from South Korea, arguing that our ally should be footing a much larger portion of the bill. They currently pay more than $800 million a year, about half of what it costs to keep 28,500 soldiers on the Korean peninsula, but the Trump administration has suggested they should pay nearly the entire cost.

Now the New York Times reports that Trump has ordered the Pentagon to draw up options for reducing the number of U.S. troops in South Korea. While North Korean leader Kim Jong-un just had a historic meeting with South Korean President Moon Jae-in, and Trump is expected to hold his own landmark meeting with Kim in the next few weeks, officials said the troop reassessment was not meant to be a bargaining chip in negotiations. If true, that means Trump didn’t think it would be a problem to start looking at a move that could weaken the U.S.–South Korean alliance, and also aligns with Kim’s goals.

South Korea was quick to deny the story. Moon’s office told Bloomberg that a “key” official at the U.S. National Security Council told Chung Eui-yong, Seoul’s national security chief, that the report was “not true.” A spokesperson for the U.S. Joint Chiefs of Staff, Colonel Patrick Ryder, said he had no information on the Pentagon preparing troop options for the president.

Separate from the negotiations aimed at curtailing Pyongyang’s nuclear program and ending hostilities between the two Koreas, Seoul and Washington have been renegotiating the cost-sharing agreement for basing U.S. troops in South Korea, which expires at the end of the year.

Trump isn’t the only official who’s suggested it’s time to rethink the U.S. presence in South Korea. Moon Chung-in, an adviser to the South Korean president, said negotiations with the North may change the calculus. “What will happen to U.S. forces in South Korea if a peace treaty is signed?” he wrote in an article published this week. “It will be difficult to justify their continuing presence.”

But the South Korean government said U.S. troops are still needed, and the Times reported that officials at the Pentagon and other agencies were “rattled” by Trump’s directive. The presence of U.S. troops and their families is seen as a key deterrent that’s kept more serious hostilities from breaking out on the Korean peninsula.

While Kim has long insisted that U.S. troops leave the peninsula, and railed against the annual U.S.–South Korean military exercises, Moon said last week that he’d dropped his demands for a U.S. exit in exchange for denuclearization. So why would Trump order the Pentagon to look into troop withdrawal? Victor Cha, who was dropped from consideration to be ambassador to Seoul several months ago, told the Times that the move would appeal to Trump’s base, save the U.S. money, and give him a bargaining chip for when he talks to Kim.

“But from the perspective of the U.S.–South Korea alliance,” Mr. Cha said, “it would represent a major retrenchment.”

One might think that Trump’s top priority during this sensitive time would be avoiding any move that could weaken our ally’s position in talks with Kim. Could it be that Trump isn’t the master negotiator he claims he is?