"We will stop the war games which will save us a tremendous amount of money", Trump said.
The Pentagon declined to flesh out Trump's remarks about suspending drills, a move the U.S. military had long resisted, saying it was working with the White House, U.S. allies and partners "on the way forward following the summit".
"There were no surprises, they had spoken on all of these issues in advance", Dana White, the chief Pentagon spokesperson, told ABC News when asked if Mattis knew about the president's announcement.
"Conversations have been robust, there were no surprises".
All the experts in attendance, including the delegation from China, were unanimous in their belief that peace and diplomatic relations could not be restored if the leaders of United States and North Korea could not meet and speak. That would have put us in a precarious position because it would have paved the legal pathway for the removal of USA troops from South Korea.
In a statement, the top United States military headquarters in South Korea said that they have "received no official updated guidance on execution or cessation on any upcoming training exercises".
Photo of Merkel and Trump captures G7 tensions
German Chancellor Angela Merkel commented on the possible return of Russian Federation to the G8 format. The legality of the decisions at that time was confirmed by the European Court of Justice.
Colonel Rob Manning, another spokesman, said: "We are going to be aligned with the president", while noting that the readiness of USA forces would remain "paramount".
"The UN Security Council resolutions that have been passed say that if North Korea respects and acts in accordance with the resolutions, then sanction measures can be adjusted, including to pause or remove the relevant sanctions", a Foreign Ministry spokesman, Geng Shuang, said at a daily news briefing. That's not part of the equation.
About 28,500 USA troops are stationed in South Korea, a legacy of the Korean War, which ended in 1953 in an armistice that left the two Koreas technically still at war.
And what "exactly was the president committing to?" he added.
The exercises are held several times each year, focusing on everything from warding off a North Korean attack on its neighbour to the south to "decapitation" strikes aimed at killing key members of the Kim regime.
"North Korea is a small and weak country surrounded by big powers and that has made North Koreans paranoid about their own national security and develop nuclear weapons, " said Yoon, speaking on Bloomberg Television. "The only way to get stability in Northeast Asia is to begin to see a moderation of North Korean politics and society. and America should be part of that process", said Ross, who believes that the world must become resigned to North Korea being a nuclear power.
Trump's remarks contradicted decades of assertions by USA administrations that military exercises in South Korea are defensive and essential to ensuring that allied forces are ready at a moment's notice to fight the North. But the joint exercises, which the US has described as a security and peacekeeping measure, have always been a sticking point; North Korea, which views the exercises as practice for an invasion, had threatened to cancel the summit over them.