Invading Ukraine would be a “strategic mistake” that would lead to “severe consequences for Russia,” United Kingdom Foreign Secretary Liz Truss said Friday ahead of a weekend G7 meeting in Liverpool, BBC reports.

Around 94,000 Russian troops have massed on the Ukrainian border, and intelligence estimates obtained by The Washington Post suggest that the invasion could come as early as January 2022 and involve 175,000 troops. CIA Director William Burns warned Monday that the build-up of military forces could allow Russia to act “in a very sweeping way.”

Truss urged European leaders to reduce their dependence on Russian natural gas and suggested that the U.K. might take steps to lock Russian money out of British financial markets.

When asked if she could rule out a military response, Truss said the U.K. is working to bolster Ukraine’s “defence and security capability.”

During a Tuesday call with Russian President Vladimir Putin, U.S. President Joe Biden ruled out the possibility of the U.S. unilaterally sending troops to defend Ukraine if Russia invades, but he did warn Putin that Russia would face economic sanctions “like nothing he’s ever seen.” According to RAND Corporation analyst William Courtney, military aid would also be on the table and could take the form of anti-tank and anti-aircraft launchers, drones, and helicopters.

Putin has repeatedly accused Ukraine of provocations and objected to NATO activities within what he regards as Russia’s natural sphere of influence. Ukraine ousted a pro-Putin government in 2014 and has drifted closer to the West ever since.

Support for joining NATO among Ukrainians reached 54 percent this year, up 40 percent from 2012.