SEOUL — 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.

The top U.S. negotiator, James DeHart, said the U.S. side decided to cut short the negotiations on Tuesday morning, the second of two days of planned talks. In a rare public show of disunity between the allies, he blamed South Korea for making proposals that “were not responsive to our request for fair and equitable burden sharing.”

“As a result we cut short our participation in the talks today in order to give the Korea side time to reconsider,” he said in a statement. “We look forward to resuming our negotiations when the Korean side is ready to work on the basis of partnership, on the basis of mutual trust.”

This year, South Korea agreed to pay about $890 million toward the cost of stationing U.S. troops in the country, a little more than 40 percent of the day-to-day expenses. It also provides land for bases rent-free, paid more than 90 percent of the $10.7 billion cost of moving the main U.S. base out of Seoul, and buys significant amounts of U.S. military equipment.

But Trump insists that South Korea, as a “very wealthy nation,” needs to pay more. His demand for up to $5 billion would imply South Korea was effectively not only being asked to cover local costs but also the entire wage bill for the U.S. troops.

South Korea’s top negotiator, Jeong Eun-bo, said there is a “significant difference” between proposals put forward by the two sides.

“The United States believes that the share of defense spending should be increased in large amounts by such means as creating a new category,” South Korea’s Foreign Ministry said in a statement, adding that it had argued for payment within a “mutually acceptable range” on the basis of an agreement that had been in place for 28 years.

On Sunday, the allies announced they were postponing planned joint air drills to save a faltering dialogue process with North Korea. But negotiator Jeong said there had been no discussion of reducing the U.S. troop presence in the country.

South Korean lawmaker Lee Hye-hoon said in a radio interview on Tuesday that the U.S. ambassador to South Korea, Harry Harris, repeatedly pushed her about the fivefold increase, saying Seoul only covers one-fifth of the necessary contributions.

Hours after the negotiations broke down in Seoul, U.S. Defense Secretary Mark T. Esper told reporters in Manila that South Korea is a “wealthy country” that “can and should contribute more.”

Last week, a group of 47 left-leaning South Korean lawmakers issued a statement condemning the Trump administration’s approach to the negotiations and arguing that Seoul needed to become self-reliant for its national defense. Conservative lawmakers have also expressed concerns.

Around 300 protesters gathered outside the venue where the talks began Monday accusing the United States of “robbery,” South Korea’s Yonhap News Agency reported.

Seoul and Washington aim to reach a new cost-sharing deal by the end of this year, when the current agreement expires. The Trump administration is set to begin separate defense funding negotiations with Japan and NATO next year.