The remarks by Mattis at a security forum in California came a day after President Donald Trump held informal talks with Putin on the sidelines of the Group of 20 industrialized nations meeting in Argentina. Trump had scrapped a more formal meeting with Putin, citing Russia’s treatment of Ukraine.
Asked if U.S.-Russian ties had become more strained since he took over the Pentagon last year after Trump became president, Mattis said, "There’s no doubt the relationship has worsened."
"(Putin) tried again to muck around in our elections this last month. And we are seeing a continued effort along those lines," Mattis said, adding that the United States would take whatever steps were necessary to defend American democracy.
American intelligence agencies concluded that Russia interfered in the 2016 U.S. presidential election to sow discord and boost Trump’s chances through a campaign of propaganda and hacking aimed at disparaging his Democratic opponent Hillary Clinton. A special counsel investigation into Russia’s role in that election and whether Trump’s campaign conspired with Moscow has cast a cloud over his presidency.