(CNN) In his last public remarks as national security adviser, Lt. Gen. HR McMaster offered harsh words for Russia Tuesday during a speech at the Atlantic Council in Washington DC.

"We have failed to impose sufficient costs" on Russia, McMaster said at the event, which also included a Q&A with the Presidents of Estonia and Latvia, as well as the Foreign Minister of Lithuania.

He added that the failure to impose adequate costs on Russia's activities meant that "the Kremlin's confidence is growing."

"Russia has used old and new forms of aggression to undermine our open societies," McMaster said.

"For too long some nations have looked the other way," McMaster said, cataloging what he said were a series of actions by Russia that warranted condemnation, including cyberattacks against the US and its NATO allies, and unsafe intercepts of US and NATO military forces.

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