By Humeyra Pamuk, Dmitry Antonov and Jeff Mason
WASHINGTON/MOSCOW (Reuters) - U.S. President Joe Biden said on Tuesday he would consider personal sanctions on President Vladimir Putin if Russia invades Ukraine, as Western leaders stepped up military preparations and made plans to shield Europe from a potential energy supply shock.
The rare sanctions threat came as NATO places forces on standby and reinforces eastern Europe with more ships and fighter jets in response to Russia's troop build-up near its border with Ukraine.
Russia denies planning an attack and says the crisis is being driven by NATO and U.S. actions. It is demanding security guarantees from the West, including a promise by NATO never to admit Ukraine. Moscow sees the former Soviet republic as a buffer between Russia and NATO countries.
Following multiple rounds of U.S.-Russia talks over Ukraine that failed to reach a breakthrough, Biden, who has long warned Moscow of economic consequences, upped the ante on Tuesday by saying Putin could personally face sanctions.