China said on Tuesday it is glad to see Moscow and Washington improve their relations, a comment that came as US President Donald Trump triggered a tsunami of criticism at home for his "weak" and "treasonous" performance at a news conference on Monday with Russian President Vladimir Putin.

"China hopes the two countries will strengthen communication and dialogue and expand their cooperation, which will benefit world peace and development as well as unite the international community to jointly tackle common challenges," Foreign Ministry spokeswoman Hua Chunying said in Beijing.

"We have confidence in the China-Russia comprehensive strategic partnership of coordination, which will not be affected by any external factors," she said, adding that "our position on developing relations with the US is consistent and clear".

Back in the US, many, who had expected Trump to confront Putin over alleged meddling in the 2016 US presidential election, were alarmed at Trump's talk at the news conference when he said that Putin had given him an "extremely strong and powerful" denial of Russian involvement.

The summit on Monday in Helsinki, Finland, came three days after the US Justice Department announced its indictment of 12 Russian intelligence officers on charges they hacked Democratic Party emails.

Trump blasted the prolonged probe of Russian interference as "a disaster for our country" and "a total witch hunt".

Senator John McCain, a Republican from Arizona, said Trump delivered "one of the most disgraceful performances by an American president in memory". Former CIA director John Brennan, a Democrat, said in a tweet that Trump's comments were "nothing short of treasonous".

In a tweet later, Trump said, " ... We cannot exclusively focus on the past — as the world's two largest nuclear powers, we must get along!"

Senator Rand Paul, a Republican from Kentucky, was among the few who defended Trump.

Ted Carpenter, a senior fellow of defense and foreign policy studies at the conservative Cato Institute, said that given the "hysteria and Russophobia" in the US, it will be difficult and even impossible for Trump to reverse the dangerous deterioration in USRussian relations. "That situation does not improve prospects for global peace," he said.