Mr Trump stunned many observers at the Singapore summit when he declared he wanted to end “very provocative” war games with South Korean forces. He said the US paid for the majority of them and they were “very expensive”. “We fly in bombers from Guam,” he said.
The announcement came as a surprise to most, including the government and military of South Korea, and the 28,500 US troops stationed in the country.
On Wednesday, secretary of state Mike Pompeo flew to Seoul to explain Mr Trump’s plan – seen as a major concession to North Korea and Kim Jong-un – to the foreign ministers of South Korea and Japan.
Senator Lindsey Graham of South Carolina said he supported Mr Trump’s decision, but for a different reason; he said it was important “to give North Korea some breathing space to see if we can get a deal”.
He said Mr Trump’s complaint about the cost was “ridiculous”, adding to CNN: “The money we spend training with our allies is money well spent.”
“It’s not a burden onto the American taxpayer to have a forward deployed force in South Korea. It brings stability. It’s a warning to China that you can’t just take over the whole region,” said Mr Graham, a member of the Senate Armed Forces Committee.
“So I reject that analysis that it costs too much, but I do accept the proposition, let’s stand down and see if we can find a better way here.”
Mr Trump told reporters in Singapore he wanted to halt the exercises, which includes Ulchi Freedom Guardian, one of the largest military exercises in the world.
The war games spread over 11 days and involve thousands of US and South Korean troops, an event North Korea has long described as being a deliberate provocation.
“Under the circumstances that we’re negotiating a very comprehensive, complete deal I think it’s inappropriate to have war games. … It is something that [North Korea) very much appreciated,” he said.
He then cited the cost of the exercises. “We fly in bombers from Guam.”
“That’s a long time for these big massive planes to be flying to South Korea to practice and then drop bombs all over the place and then go back to Guam,” he added: “I know a lot about airplanes. It’s very expensive.”
Meanwhile, other Republicans voiced concerns that Mr Trump had appeared too gushing when he spoke about Mr Kim.
Mr Trump continued to praise him on Twitter on Wednesday as he flew back to Washington via Hawaii.
Reuters quoted Republican Senator John Kennedy as saying Mr Trump had to be vigilant as the process moved forward.
“It’s important that we don’t lose sight of the fact that Kim Jong-un is a butcher and he’s a butcher of his own people,” he said.
“Trying to reason with someone like that is like trying to hand-feed a shark. It doesn’t mean that you can’t do it, but you’ve got to do it very, very carefully.”
Senator Marco Rubio, who campaigned unsuccessfully against Mr Trump in the 2016 Republican presidential primaries, also faulted Mr Trump’s praising of Mr Kim. “Kim “is NOT a talented guy. He inherited the family business from his dad & grandfather. He is a total weirdo who would not be elected assistant dog catcher in any democracy,” he said on Twitter.
House Speaker Paul Ryan said in a statement: “We must always be clear that we are dealing with a brutal regime with a long history of deceit. Only time will tell if North Korea is serious this time, and in the meantime we must continue to apply maximum economic pressure.”
Meanwhile, Democrats were much more scathing.
“It’s clear that Kim Jong-un walked away from Singapore with exactly what he wanted – the pomp, circumstance and prestige of a meeting with the president of the United States – while making no specific commitments in return,” said Mark Warner, the top Democrat on the Senate Intelligence Committee.
“Whether this will result in a verifiable agreement to dismantle North Korea’s nuclear weapons programme, America and the world will wait to find out.”