NATO Secretary-General Jens Stoltenberg warned on Wednesday against Russia's war in Ukraine sliding into a nuclear confrontation between Moscow and the West. "Russia should stop this dangerous irresponsible nuclear rhetoric," NATO secretary-general told a news conference, reports Reuters.

He said, "But let there be no doubt about our readiness to protect and defend allies against any threat anytime." Russia must understand that it can never win a nuclear war," he said on the eve of a summit of the Western military alliance's national leaders in Brussels. "NATO is not part of the conflict ... it provides support to Ukraine but isn't part of the conflict."

"NATO will not send the troops into Ukraine... It is extremely important to provide support to Ukraine and we are stepping up. But at the same time, it is also extremely important to prevent this conflict becoming a full-fledged war between NATO and Russia."