The U.S. Department of Defense says there are no signs that Moscow plans to use nuclear weapons, according to Reuters.

"We have not seen any reason to adjust our own strategic nuclear posture nor any indications Russia is preparing to use a nuclear weapon," a senior U.S. administration official said.

The Pentagon also said the United States remains committed to the collective defense of the NATO alliance.

The representative of the U.S. Department of Defense said the United States still sees no reason to change the readiness of its nuclear forces, as well as Russia's readiness to use nuclear weapons.