U.S. President Donald Trump speaks about the shootings in El Paso and Dayton in the Diplomatic Room of the White House in Washington, U.S., August 5, 2019. REUTERS/Leah Millis

WASHINGTON (Reuters) - President Donald Trump said on Wednesday discussions have begun with South Korea, aimed at getting the country to pay more for the cost of maintaining U.S. troops in the region to guard against any threat from North Korea.

“Talks have begun to further increase payments to the United States. South Korea is a very wealthy nation that now feels an obligation to contribute to the military defense provided by the United States of America,” Trump said in a Twitter post.

A South Korean foreign ministry official said negotiations have not officially started. The two countries agreed to discuss the defense cost sharing issue “in a reasonable and fair manner” when U.S. national security adviser John Bolton visited South Korea last month, the official said, adding the details would be discussed at the next talks.

Trump has repeatedly said Seoul should bear more of the burden of keeping some 28,500 U.S. troops stationed in South Korea, where the United States has had a military presence since the 1950-53 Korean War.

South Korean and U.S. officials signed an agreement in February, under which Seoul would raise its contribution to just under 1.04 trillion won ($927 million), an increase of about $70.3 million. The interim agreement was due to expire in a year.

Trump’s tweet comes ahead of U.S. Secretary of Defense Mark Esper’s first official visit to Seoul as part of a tour through Asia in August. U.S. and South Korean militaries are planning to stage a joint exercise this month as well.