The U.S. State Department says President Donald Trump has been clear about his position on Washington’s cost-sharing deal with Seoul to station U.S. troops on the peninsula and wants South Korea to pay more.

At a press briefing on Thursday, State Department spokesperson Morgan Ortagus said “burden sharing is a theme of the President’s” as it relates to U.S. allies, including South Korea, adding “he wants all countries to share in the mutual defense.”

South Korea is facing increased pressure from the Trump administration to pay more for the upkeep of 28-thousand-500 American troops on the Korean Peninsula.

On Wednesday, Trump claimed on Twitter that bilateral negotiations on the issue have begun and Seoul “has agreed to pay substantially more.” Seoul denied both these claims. 

Under the current one-year agreement set to expire on December 31, Seoul agreed to pay one-point-04 trillion won this year, an increase of eight-point-two percent from 960 billion won last year.

Trump's remarks come ahead of U.S. Secretary of Defense Mark Esper's visit to Seoul on Friday for talks on pending alliance issues, including the defense cost-sharing deal.