Biden told Ukraine's president that the US was committed to its 'sovereignty and territorial integrity' if Russia invades

• Biden spoke with Ukrainian President Volodymyr Zelensky on Sunday.
• Biden said the US "will respond decisively" if Russia invades Ukraine.

In a call on Sunday, President Joe Biden told Ukrainian President Volodymyr Zelensky that the US "will respond decisively" if Russia should invade.

"President Biden underscored the commitment of the United States and its allies and partners to the principle of 'nothing about you without you.' He reaffirmed the United States' commitment to Ukraine's sovereignty and territorial integrity," the White House said in a statement.

The principle of 'nothing about you without you,' refers to the notion that no policy decisions would be taken without the representation of the Ukrainians. The statement added that the US and its allies have expressed support for diplomatic efforts including bilateral dialogue through NATO and the Organization for Security and Cooperation in Europe next week.

On Sunday, Democratic Rep. Adam Schiff also said economic sanctions against Russia may be the strongest way to deter them from invading Ukraine, warning that the possibility seemed "very likely."

Russian President Vladimir Putin warned Biden last week that US sanctions "could lead to a complete breakdown in ties between our countries."

Biden has previously asked Putin to ease tensions with Ukraine and warned that the US would step in if Russia invades.