European leaders are blasting Russia's decision to cut natural gas shipments to Poland and Bulgaria as "blackmail."
A memo from the state-controlled Russian gas giant Gazprom says it cut natural gas deliveries to the two nations because they refuse to pay in Russian rubles, a recent demand by the Kremlin.
Russia's cutoff could lead to gas rationing in the two nations. especially Bulgaria. But it could also deprive Russia of badly needed income to pay for its war effort.
Poland was already in the process of phasing out Russian natural gas in its energy supply and Poland's prime minister said the nation will be able to protect its economy.
Russian President Vladimir Putin also warned there would be lightning-fast retaliation if anyone from outside Ukraine tries to intervene and poses a threat to Russia.
Putin said, "If someone intervenes in events from the outside, it will create strategic threats unacceptable for us, they should know that our response to counter strikes will be immediate and quick.
He avoided any specific mention of nuclear weapons, but his foreign minister this week said the risk of nuclear war is a real one.
The warning came amid reports of explosions in three Russian cities not far from the Ukrainian border.
In the midst of the fighting, the U.S. and Russia did engage in a prisoner swap Wednesday, exchanging former U.S. Marine Trevor Reed for a Russian pilot in jail in the U.S. on drug charges.
Russian TV showed Reed on a tarmac in Turkey walking to freedom, passing the convicted Russian felon swapped for his release.
His parents said their son looked frail.
"He looked like he could hardly walk, he looked like he'd been walking shackled. We started crying," his father Joey Reed said.
Two other Americans are still in Russian custody, another former Marine Paul Whelan, and WNBA basketball star Brittney Griner.