US, Allies Shrug Off Russia Nuclear Warning

But in a move that sharply raises the economic stakes for the West, Russia said it would turn off gas supplies to Poland on Wednesday morning after weeks of threats that it would cut off supply to countries who refuse to pay for gas in roubles.

Poland, a key NATO ally of the United States and among the European countries seeking the toughest possible sanctions against Russia, said it had sufficient gas reserves.

Russia's defence ministry said its forces had "liberated" the entire Kherson region in southern Ukraine and parts of the Zaporizhzhia, Mykolaiv and Kharkiv regions, Interfax news agency reported. If confirmed, that would represent a significant Russian advance across eastern and southern Ukraine.

One of President Vladimir Putin's closest allies, Nikolai Patrushev, said Ukraine was spiralling towards a collapse into "several states" due to what he cast as a US attempt to use Kyiv to undermine Russia. His comments seemed to be an effort to blame Washington for any break-up of Ukraine that emerges from the war, now in its third month.

US Defense Secretary Lloyd Austin, welcoming officials from more than 40 countries to Ramstein Air Base in Germany, headquarters of US air power in Europe, said: "Nations from around the world stand united in our resolve to support Ukraine in its fight against Russia's imperial aggression.

"Ukraine clearly believes that it can win, and so does everyone here," he said.

The United States has ruled out sending its own or NATO forces to Ukraine but Washington and its European allies have supplied Kyiv with arms including howitzer heavy artillery, drones and anti-aircraft Stinger and anti-tank Javelin missiles.

In a notable shift, Germany, which had come under pressure after refusing Ukrainian pleas for heavy weapons, announced it would send Gepard light tanks with anti-aircraft guns. Washington welcomed Berlin's move.

US officials, speaking on condition of anonymity, believe Russia will rely heavily on artillery strikes to pound Ukrainian positions while moving in ground forces from several directions to try to envelop and wipe out much of Ukraine's military.

But Washington also estimates that many Russian units are depleted, with some operating with personnel losses as high as 30% - a level considered by the US military to be too high to keep fighting indefinitely.