Posturing by Russia to divide NATO and split the EU from the US. Russia would also benefit if they maneuvered the US into being the aggressor in a war. There is also a major NATO summit this summer and I imagine that this posturing is an attempt to dissuade Ukraine from attempting to join NATO or join a path to membership. If that ever happened, I believe Putin would invade the Ukraine, as he views it as essential to Russia's security and has publicly declared that as a red line. The US on the other hand is not a serious country and has no serious interests in Ukraine that would warrant a potential nuclear exchange with Russia. It's a lose-lose situation for the US since they are experiencing a serious lack of legitimacy after the Afghanistan defeat and now they are putting themselves in the position to either have to go to war with Russia over marginal interests, or lose even more face on the international stage when Russia doesn't invade and the US looks like an unhinged instigator.