The U.S. Senate voted in a rare bipartisan moment late Thursday to send a show of support for an independent Ukraine and warn against Russian military aggression toward its neighbor as fresh fears emerged of a possible invasion that could spiral toward a European war.

Action in the Senate came after President Joe Biden said the U.S. has “every indication" of a potential Russian attack on Ukraine in a matter of days. U.S. officials have outlined stark scenarios of President Vladimir Putin's potential plans as Russian troops remain massed at the Ukraine border.

The resolution from the senators does not carry the force of law but puts the U.S. legislative body on record supporting Ukraine and condemning Russian aggression. The vote was unanimous, without objection or the formal roll call.

“This Congress is united in its support of Ukrainian independence and sovereignty," said Sen. Rob Portman, R-Ohio, in introducing the measure with Democratic Sen. Jeanne Shaheen of New Hampshire and others.

Senators have been racing all week to mount a response to rising tensions in the region, many eager to go even further by imposing devastating sanctions on Putin that would send shockwaves through the Russian economy.

Ukraine has strong allies in the Senate, where there is broad support for sanctions on Russia as a powerful foreign policy tool to be used if Putin furthers his aggression toward Ukraine.

Amid high-stakes diplomatic efforts to pull Russia off any plans to invade, senators held back on legislation sanctioning Russia, deferring to the White House's own strategy for easing out of the crisis that could spread across Europe.

Senators have said the administration can impose sanctions on its own, regardless of congressional action.

“It is not a question of ‘if’ but ‘how’ we will respond to Putin,” said Shaheen in a statement.

Earlier this week, Senate leaders, along with the Democratic chairmen and top Republicans on the foreign relations and other committees, issued a bipartisan statement ahead of the resolution.

Despite widespread backing from the senators for legislation that would sanction Russia over its behavior toward Ukraine, they have had debates over the details and timing. There have also been differences over the Nord Stream 2 energy pipeline between Russia and Germany, although those may have become resolved after Biden said last week the energy line would not continue if Russia invades Ukraine.

Still, senators were eager for a unified show of support for Ukraine at this moment, and before the Senate recessed. Several senators and House lawmakers were headed to an annual security conference in Munich.

The resolution Thursday encourages Biden to have the U.S. government exhaust its tools available to impose costs on Russia and restore peace in Europe.