Outgoing Trump aide HR McMaster : US should be tougher on Russia
General H.R. McMaster (Photo: Screen capture)

President Donald Trump's departing national security advisor HR McMaster said Washington has not gone far enough to punish Russia for interfering in US elections and using a nerve agent to poison a former spy in England.

In a speech late Tuesday to the Atlantic Council ahead of his exit from the White House, McMaster told the leaders of Latvia, Estonia and Lithuania and others that Russia remains a threat to open societies and international peace.

He cited the attempted assassination in England of former Russian spy Sergei Skripal and his daughter Yulia with a banned nerve agent and the "pernicious" employment of submilitary forms of aggression to attack rivals as evidence that Moscow has not been deterred.

"For too long some nations have looked the other way in the face of these threats. Russia brazenly and implausibly denies its actions. And we have failed to impose sufficient costs," McMaster said.

Analysts saw McMaster's statement as a criticism of Trump, who has consistently tempered his remarks on the Russian president.

The statement came hours after Trump defended his embrace of Vladimir Putin, saying good relations were important and that he had been tougher than anyone else on Russia.

"Probably nobody's been tougher to Russia than Donald Trump," the president said during White House meetings with the leaders of the three Baltic countries -- all of whom say they worry deeply about the threat from the powerful giant on their borders.

"If we got along with Russia, that would be a good thing not a bad thing," said Trump, who recently proposed a White House summit with Putin.

"I think I could have a very good relationship with President Putin," he said.

McMaster, however, warned that Moscow menaces the US way of life, and that Putin has not yet been deterred.

"The Kremlin's confidence is growing as its agents conduct their sustained campaigns to undermine our confidence in ourselves and in one another," he said.

"Russia employs sophisticated strategies deliberately designed to achieve objectives while falling below the target state’s threshold for a military response."

"Mr Putin may believe that he is winning in this new form of warfare."

Last month the United States joined nearly 30 European allies in expelling a total of 150 Russian officials, many labelled intelligence agents, to punish Moscow for the attempted murder of Skripal.

On Wednesday the US Director of National Intelligence, Dan Coats, said the attack on Skripal was "almost like the final straw" and that the US is weighing more actions against Moscow.

"We clearly are in a position now to be undertaking the prospect of additional reactions to this issue," he told reporters.

"This is under considerable consideration and more things will be done, and soon, above where we are right now. Stay tuned on that," he added.