US Defence Secretary Ash Carter has said that Russia "has clear ambition to erode the principled international order" through coercion and aggression.
"Russia appears driven by misguided ambition and misplaced fear," Mr Carter said in a speech to students at Oxford University.
He used the address to criticise Russia's "unprofessional behaviour" in Ukraine, Syria and cyberspace, and he accused Moscow of nuclear "sabre rattling."
Russia, he said, wants to sow instability beyond its borders, including in the Middle East. At the same time, he urged Moscow to take a more constructive role in Syria to arrange a lasting ceasefire.
"Despite the progress that we made together in the aftermath of the Cold War, Russia's actions in recent years - with its violations of Ukrainian and Georgian territorial integrity, its unprofessional behaviour in the air, in space, and in cyberspace, as well as its nuclear sabre rattling - all have demonstrated that Russia has clear ambition to erode the principled international order," Mr Carter said.
Also on Wednesday, the Kremlin said the latest round of US sanctions against Russia ran counter to potential cooperation on "sensitive issues" that President Barack Obama and President Vladimir Putin discussed during their meeting this week during an economic summit in China.
The US Department of Commerce has added 11 companies linked to the Russian arms sector to the sanctions list that the Obama administration compiled immediately after Russia's annexation of Crimea. The move restricts the companies' exports to the United States.