Secretary of Defense Jim Mattis says Russia tried to interfere in the November 2018 elections and that there is 'no doubt' the relationship between Russia and the U.S. has worsened in the past couple of years. (Clip: Reagan Foundation)

WASHINGTON — Defense Secretary Jim Mattis on Saturday took aim at Russian President Vladimir Putin, accusing him of trying to “muck around” in the U.S. midterm elections, of duplicity in arms control and of acting irresponsibly in last weekend’s naval confrontation with Ukraine.

In remarks at the Reagan National Defense Forum in Simi Valley, California, Mattis said the U.S.-Russian relationship has deteriorated over the last two years.

"We are dealing with someone that we simply cannot trust," he said. "There is no doubt the relationship has worsened."

Mattis did not elaborate on his claim that Russia tried to interfere in last month’s elections, adding only, “We are seeing a continued effort along those lines.” He added more generally, “It’s his efforts to try to subvert democratic processes that must be defended.”

Citing Russia’s seizure of Ukrainian vessels and sailors, President Donald Trump canceled his plans to meet with Putin at this weekend’s Group of 20 summit in Argentina, but he said he looked forward to meeting Putin soon. Russian Foreign Minister Sergey Lavrov called the canceled Trump-Putin meeting a missed opportunity, saying it didn’t “help settling a number of important international problems.”

The naval incident further escalated a tug-of-war that began in 2014 when Russia annexed Ukraine's Crimean Peninsula and supported separatist rebels in eastern Ukraine. It also has prompted global concern and renewed Western criticism of Russia. Mattis portrayed the latest incident as evidence that the administration's defense strategy, announced nearly a year ago, was correct in refocusing from the post-9/11 wars to what Mattis has called an emergence of "great power" competition with Russia and China.