The United States on Saturday urged Russia to pull back from the brink over Ukraine, warning that the G7 and its allies will impose tough measures if it abandons diplomacy.
A senior State Department official told reporters at a meeting of the grouping's top diplomats in Liverpool, northwest England, that Moscow still had time to change course.
"But if they choose not to pursue that path, there will be massive consequences and severe costs in response, and the G7 is absolutely united in that," the official said.
"A large number of democratic countries will join us in imposing costs," they added.
The warning came as Russian sabre-rattling against Ukraine and how to counter an increasingly assertive China dominated the first day of a two-day meeting of G7 foreign ministers in the British city.
The meeting — at which ministers want to present a united front against authoritarianism — is the last in-person gathering of Britain's year-long G7 presidency, before it hands the baton to Germany.
Opening the talks, Britain's Foreign Secretary Liz Truss told delegates: "We need to come together strongly to stand up to aggressors who are seeking to limit the bounds of freedom and democracy.
"To do this, we need to have a fully united voice. We need to expand our economic and security posture around the world."
Truss, in the job since September, set out her foreign policy vision in a major address on Wednesday, echoing U.S. threats of unprecedented sanctions if Russia invades Ukraine.
Western concerns are growing over a Russian troop build-up on the border that the Kremlin says is defensive against any move by the former Soviet state eastwards towards NATO.
G7 ministers want to show the grouping can move beyond condemnation to robustly defend its values as a deterrent to future threats.
The meeting comes after U.S. President Joe Biden this week held a virtual summit with his Russian counterpart Vladimir Putin to try to end the stand-off diplomatically.
Washington's top diplomat for Europe and Eurasian affairs, Karen Donfried, jets to Kiev and Moscow next week for follow-up talks with senior government officials.
She will then head to Brussels for further discussions with NATO and EU allies.