PYEONGTAEK, South Korea (Reuters) - The chief of the U.S. military forces commended South Korea for shouldering nearly all the cost of building the largest U.S. overseas military base, in a speech at the formal opening of the new headquarters in Pyeongtaek.

“This was a project that cost nearly $10.8 billion to build over 10 years and the Republic of Korea investment was over 90 percent of the cost,” Commander Vincent Brooks said at the base, around 65 kilometers (40 miles) south of Seoul.

“For that 90 percent, the United States remains with you 100 percent.”

U.S. President Donald Trump has repeatedly stressed since before taking office that Seoul should burden more of the expenses needed for the upkeep of some 28,500 U.S. troops in South Korea.

After his summit with North Korean leader Kim Jong Un in Singapore on June 12, Trump made a surprise announcement that the United States will stop joint military drills with South Korea, saying they are “very expensive” and paid for mostly by Washington.

Officials in both the United States and South Korea have declined to specify how much the exercises cost each party.

The two countries are currently in talks over how to share the costs of keeping the U.S. troops in South Korea starting 2019. An existing accord, signed in 2014 and due to expire at the end of 2018, requires Seoul to pay about 960 billion won ($856.6 million) this year.

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The previous headquarters of the U.S. Forces Korea (USFK) had been located at the heart of Seoul since the 1950-53 Korean conflict, which had ended in a ceasefire and not a peace treaty.

Brooks has said the joint U.S.-South Korean Combined Forces Command (CFC) will remain in Seoul, moving into the South’s defense ministry complex. Brooks commands both the USFK and CFC.

The USFK’s previous base in Seoul will be transformed into a public park.

The base in Pyeongtaek, Camp Humphreys, is the largest overseas U.S. base in the world, straddling an area of 14.7 million square meters.

It is also the largest in terms of personnel. As of April 30, the base had 19,904 U.S. personnel in total, according to the USFK, which expects the population to reach 27,702 by the end of 2021.

The relocation project, initiated in 2004, initially intended to streamline and incorporate some 40 U.S. bases across South Korea into Pyeongtaek and the southern city of Daegu by 2008.

South Korean President Moon Jae-in lauded the opening of the new headquarters, saying recent steps toward denuclearization of the Korean peninsula were only possible due to the deterrent provided by the US-South Korea alliance, and the allies’ efforts to engage North Korea diplomatically.