Trump, who has cast himself in his second term as a global peacemaker, said he wanted a summit with his counterparts Vladimir Putin and Xi Jinping "when things calm down".

"I want to say, let's cut our military budget in half," he told reporters in the Oval Office on Thursday.

Asked about the proposal on Friday, China's foreign ministry responded that the United States had the largest military budget in the world.

"Since the United States calls for 'America First', they should take the lead in setting an example of cutting military spending," foreign ministry spokesman Guo Jiakun told a regular news briefing.

"China's military budget is open and transparent. It is reasonable and appropriate in relation to the United States and other major military powers," he said.

"China's limited defence spending is entirely necessary for safeguarding national sovereignty, safety and development interests, and is necessary for protecting world peace."

Trump also called on Thursday for the three powers to start cutting their nuclear arsenals, but Guo said that Washington and Moscow had a "special and primary responsibility for nuclear disarmament" as the countries with the most nuclear weapons.

"China... always maintains its nuclear force at the minimum level required for national security and does not engage in arms races with any country," Guo said.