U.S. President Donald Trump said on Tuesday that there should be a further increase in South Korea's share of the cost of stationing American troops on the Korean Peninsula.

Trump's remarks came only days after the allies signed a preliminary agreement renewing their cost-sharing deal for the 28,500-strong U.S. Forces Korea.

"As you know, South Korea -- we defend them and lose a tremendous amount of money," the U.S. president said at a Cabinet meeting, repeating a signature refrain.

"Billions of dollars a year defending them. They agreed, at my request. And working with Secretary (of State) Pompeo and (National Security Adviser) John Bolton, they agreed to pay, yesterday, (US)$500 million more toward their defence," he claimed. "Five-hundred million, with a couple of phone calls. I said, 'Why didn't you do this before?' They said, 'Nobody asked.' So -- it's got to go up. It's got to go up."

The cited numbers don't align with the formal announcement that South Korea agreed to increase its contribution by 8.2 percent to some $920 million (1.04 trillion won) under a one-year deal.

The previous five-year Special Measures Agreement expired at the end of last year amid an impasse over U.S. demands for as much as a twofold increase in Seoul's contribution.

Last year, Seoul paid $853 million (960 billion won) toward the wages of South Korean civilian workers at U.S. bases and other costs.