U.S. Secretary of State Antony Blinken and EU foreign policy chief Josep Borrell said the United States and Europe remained unified on not only the nature of the Russian threat to Ukraine but the consequences that Russia would face if it invaded.
Watch Blinken's remarks in the player above.
They also defended the increasingly dire warnings that a Russian invasion may be imminent.
Fears are rising about what would happen to Europe's energy supply if Russia were to invade Ukraine and then shut off natural gas exports in retaliation for U.S. and European sanctions.
Although Russian officials have not signaled they would consider cutting supplies in the case of new sanctions, Europe is dependent on Russia.
Experts have said that Western sanctions would likely avoid directly targeting Russian energy supplies. More likely, they say, would be Russia withholding gas sent through pipelines crossing Ukraine.
The Biden administration has been talking with gas producers worldwide about whether they can boost output and ship to Europe, and it has been working to identify supplies of natural gas from North Africa, the Middle East, Asia and the U.S.
The administration also is talking with buyers about holding off.
In 2015, France and Germany helped broker a peace deal for eastern Ukraine in a bid to end the conflict between Ukrainian forces and Russia-backed separatists that erupted the previous year following the Russian annexation of Ukraine's Crimean Peninsula.
The agreement signed in the Belarusian capital of Minsk helped stop large-scale fighting, but efforts at a political settlement have stalled and frequent skirmishes have continued along the tense line of contact in Ukraine's industrial heartland known as the Donbas.
Putin and his officials have urged France, Germany and other Western allies to encourage Ukraine to fulfill its obligations under the 2015 agreement, which envisaged a broad autonomy for the Donbas region and a sweeping amnesty for the separatists. The agreement stipulated that only after those conditions are met would Ukraine be able to restore control of its border with Russia in rebel regions.
The Minsk deal was seen by many Ukrainians as a betrayal of national interests, and its implementation has stalled.
However, at Monday's press conference, Blinken told reporters,"Over the last years, Ukraine has sought to move forward with the implementation of Minsk," adding, "while Russia has made good on virtually none of its obligations under Minsk."