South Korea has been in talks with the campaign camp of key U.S. presidential candidates, including Republican front-runner Donald Trump, to improve each other's understanding of foreign policy issues, the Foreign Ministry said Tuesday.

Concerns have grown in South Korea as Trump has made repeated claims that South Korea is getting a free ride on defense and paying little for the upkeep of U.S. troops on its soil. The real-estate mogul has also said he would allow South Korea and Japan to go nuclear.

Seoul has so far refrained from commenting on such accusations, saying it does not interfere in the domestic politics of another country.

However, responding to growing calls for the government to address the issue, a ministry spokesman stressed that South Korea continues to make large contributions to the U.S. military presence here and remains committed to keeping nuclear weapons off the peninsula.

"Our government contributes to and plays a role in maintaining and strengthening the South Korea-U.S. joint defense posture and creating stable conditions for the stationing of U.S. forces in Korea," Cho June-hyuck said during a regular press briefing.

"Our government is closely monitoring the U.S. presidential election and the foreign policies of key candidates," he added. "We have made and will continue to make outreach efforts to the campaigners of key candidates, including Mr. Trump, to learn about their policies on the Korean Peninsula and deliver our positions on foreign policy issues."

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.

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. (Yonhap)