Joe Biden has said there would be “enormous consequences” globally if Russia invaded Ukraine.
An estimated 100,000 or so Russian troops are amassed on the Ukraine border. Mr Biden said if Vladimir Putin were to order them to move in “it would be the largest invasion since World War II, it would change the world.”
He added: “There would be enormous consequences if he were to go in and invade ... for Russia, not only in terms of economic consequences and political consequences but enormous consequences worldwide.”
Sources told the Independent that the United States was preparing economic sanctions aiming to “maximise pain in the Kremlin” if Russia invades.
The plans, which were being discussed with partners and allies, could include export controls and financial sanctions, sources said.
They will be designed to “maximise pain the Kremlin while also minimising the spillover” elsewhere, the source said.
In the UK, Boris Johnson said he would “not hesitate” to toughen economic sanctions against Russia in the event of an invasion.