WASHINGTON • President Donald Trump has ordered the Pentagon to prepare options for drawing down US troops in South Korea, just weeks before he holds a landmark meeting with North Korean leader Kim Jong Un, according to several people briefed on the deliberations.

Reduced troop levels are not intended to be a bargaining chip in Mr Trump's talks with Mr Kim about his weapons programme, these officials said. But they acknowledged that a peace treaty between the two Koreas could diminish the need for the 23,500 soldiers stationed on the peninsula.

Mr Trump has been determined to withdraw troops from South Korea, arguing that the United States is not adequately compensated for the cost of maintaining them, that the troops are mainly protecting Japan and that decades of US military presence had not prevented the North from becoming a nuclear threat.

His latest push coincides with tense negotiations with South Korea over how to share the cost of the military force. Under an agreement that expires at the end of this year, South Korea pays about half the cost of the upkeep of the soldiers - more than US$800 million (S$1.06 billion) a year.

The Trump administration is demanding that it pay for virtually the entire cost of the military presence.

The directive has rattled officials at the Pentagon and other agencies, who worry that any reduction could weaken the US alliance with South Korea and raise fears in neighbouring Japan at the very moment that the US is embarking on a risky nuclear negotiation with the North.

Officials declined to say whether Mr Trump was seeking options for a full or partial reduction of troops, although a full withdrawal was unlikely. They emphasised that rethinking the size and configuration of the US force was overdue, regardless of the sudden flowering of diplomacy with North Korea.

But Mr Trump's meeting with Mr Kim injects an unpredictable new element. His enthusiasm for the encounter - and the prospect of ending a nearly 70-year-old military conflict between the two Koreas - has raised concerns that he may offer troop cuts in return for concessions by Mr Kim.

For Mr Trump, withdrawing troops would have multiple benefits, said Dr Victor Cha, a Korea scholar at Georgetown University.

It would appeal to his political base and save the US money.

"But from the perspective of the US-South Korea alliance," Dr Cha said, "it would represent a major retrenchment."

NYTIMES