Washington: The U.S Senate has unanimously passed a resolution condemning Russian President Vladimir Putin as a war criminal, a rare show of unity in the deeply divided Congress.

The resolution, introduced by Republican Senator Lindsey Graham and backed by senators of both parties, encouraged the International Criminal Court (ICC) in The Hague and other nations to target the Russian military in any investigation of war crimes committed during Russia's invasion of Ukraine.

"All of us in this chamber joined together, with Democrats and Republicans, to say that Vladimir Putin cannot escape accountability for the atrocities committed against the Ukrainian people," Democratic Senate Majority Leader Chuck Schumer said in a speech on the Senate floor ahead of the vote, Reuters reported.

Russia calls its actions a "special military operation" to demilitarise and "denazify" Ukraine. Putin has also called the country a U.S. colony with a puppet regime and no tradition of independent statehood.

Moscow has not captured any of the 10 biggest cities in the country following its incursion that began on Feb. 24, the largest assault on a European state since 1945.

The bipartisan measure from Sen. Lindsey Graham, R-S.C., says the Senate strongly condemns the “violence, war crimes. crimes against humanity” being carried out by Russian military forces under Putin’s direction. It encourages international criminal courts to investigate Putin, his security council and military leaders for possible war crimes.

“These atrocities deserve to be investigated for war crimes,” said Senate Majority Leader Chuck Schumer, D-N.Y.

The measure was approved swiftly and without dissent as lawmakers in Congress continue to muscle a bipartisan show of force against the Russian war in Ukraine. First introduced almost two weeks ago, the Senate resolution would not carry the force of law but is another example of Congress providing the Biden administration political support to take a tough line against Putin’s aggression.