U.S. Ambassador to Seoul Mark Lippert on Monday dismissed accusations by Republican presidential front-runner Donald Trump that South Korea is paying little to keep American troops on its soil.

Without naming Trump, Lippert cited various reasons why the allegations aren't true, including the fact that South Korea shoulders 55 percent of all non-personnel costs and increases its defense spending by 3 to 5 percent annually.

"We feel very good about the resource sharing that we and the Republic of Korea do together as an alliance," the ambassador said during a meeting with members of the American Chamber of Commerce in Korea. "It is remarkable."

Trump has made repeated claims that South Korea is getting a defense free ride, saying recently that the U.S. is "constantly sending our ships, sending our planes, doing our war games" but being "reimbursed a fraction of what this is all costing."

About 28,500 American troops are stationed in South Korea to deter North Korean aggression, a legacy of the 1950-53 Korean War that ended in a truce, not a peace treaty, leaving the divided peninsula still technically at war.

Lippert recalled his past work at senior levels in the Pentagon.

"You get a sense of the alliances and how much and who contributes what," he said. "Korea does very well in terms of its contribution."

Seoul has long shared the cost of stationing U.S. forces. 

In 2014, the two countries renewed their cost-sharing agreement, known as the Special Measures Agreement, with Seoul agreeing to pay 920 billion won for the upkeep of the U.S. troops in 2014, a 5.8-percent increase from the year prior.

Moreover, the American military presence on the peninsula is seen as in line with U.S. national interests in a region marked by a rising China.

"At the end of the day, I think the U.S. government feels very, very good about the resource sharing, the burden sharing we're engaged in," Lippert said.

Calling the bilateral relationship "one of the premier military alliances around the world, he added, "It works, it's effective and both sides have a lot invested in the success of this alliance." (Yonhap)