The day after he tried to quiet a political uproar over his failure to confront Russian President Vladimir Putin during their Helsinki summit for Moscow's 2016 election meddling, Trump adopted his usual defiant posture and dismissed assessments of Russia from the intelligence community.

"We're doing very well, probably as well as anybody has ever done with Russia. And there's been no president ever as tough as I have been on Russia," Trump said before a Cabinet meeting at the White House, adding that Putin "understands it and he's not happy about it."

Asked by reporters whether Russia was still targeting the United States, Trump shook his head and said, "No."

US intelligence officials have said Russian election interference efforts are continuing and now target the upcoming congressional elections in November.

Trump's comments followed a series of early morning Twitter posts on Wednesday in which the Republican president said his heavily criticised summit with Putin would eventually produce "big results" and accused his critics of "Trump Derangement Syndrome."

"Some people HATE the fact that I got along well with President Putin of Russia. They would rather go to war than see this. It's called Trump Derangement Syndrome!," the president wrote.

Trump has faced bipartisan fury at home since the summit in Finland.

Critics have accused him of siding with Russia over his own country by failing to criticise Moscow for what US intelligence agencies last year described as Moscow's interference in the 2016 election in an attempt to sow discord, aid Trump's candidacy and disparage Trump's Democratic opponent Hillary Clinton.

Putin has denied allegations of election interference.

White House spokeswoman Sarah Sanders told reporters at a news briefing hours later that the president's "no" was not in answer to a reporter's question, "Is Russia still targeting the US?" Sanders said Trump meant he did not want to answer questions.

"The president ... was saying 'No' to answering questions," Sanders said. "The president and his administration are working very hard to make sure that Russia is unable to meddle in our elections as they have done in the past."

Australian Associated Press