The White House on Tuesday began referring to Russian troop deployments in eastern Ukraine as an "invasion". US President Joe Biden has said this would result in the US levying severe sanctions against Moscow.
Several European leaders said earlier in the day that Russian troops have moved into rebel-held areas in eastern Ukraine after Russian President Vladimir Putin's recognized their independence.
Several Western countries have also started clamping sanctions on Russia.
The UK government on Tuesday imposed tough sanctions against five Russian banks and three super-rich oligarchs from the country over Putin’s aggressive action on the Ukraine border.
British Prime Minister Boris Johnson told the House of Commons that this is the "first tranche” of measures in response to Russian troops moving into two separatist regions of Ukraine.
German Chancellor Olaf Scholz has suspended the certification process for the Nord Stream 2 natural gas pipeline.
The undersea pipeline directly links Russian gas to Europe via Germany and is complete but not yet operating. It has become a major target as Western governments try to exert leverage on Russia to deter further military moves against its neighbour.