Mattis's remarks came soon after President Trump repeated his assertion that Russia should be invited back into the G7 group of nations.
Washington: US Defense Secretary Jim Mattis assailed Russian President Vladimir Putin on Friday, accusing him of attacking western democracy and trying to break up NATO.
Mattis's remarks came just hours after President Donald Trump repeated his assertion that Russia should be invited back into the G7 group of industrialized nations, from which it was kicked out for annexing Crimea in 2014, an event he blamed on his predecessor Barack Obama.
"For the first time since World War II, Russia has been the nation that has redrawn international borders by force of arms in Georgia and Ukraine, while pursuing veto authority over their neighbours' diplomatic, economic and security decisions," Mattis said at a US Naval War College graduation ceremony in Rhode Island.
"Putin seeks to shatter NATO. He aims to diminish the appeal of the western democratic model and attempts to undermine America's moral authority."
The Pentagon chief added that Putin's actions were designed not to directly challenge America's military prowess, but rather "to undercut and compromise our belief in our ideals."
Earlier on Friday, Trump said Russia should be invited back to the negotiating table with other industrialized countries. "A few years ago, Putin was in what was called the G8. I think it's better to have Russia in, than to have Russia out," Trump told reporters.
"Because just like North Korea, just like somebody else, it's much better if we get along with them than if we don't. So it's possible." he added.