A United States senator called in a controversial tweet for the assassination of Russian President Vladimir Putin amid Russia’s war on Ukraine.

"Is there a Brutus in Russia? Is there a more successful Colonel Stauffenberg in the Russian military? The only way this ends is for somebody in Russia to take this guy out. You would be doing your country – and the world – a great service," said U.S. Senator Lindsey Graham on Twitter, after speaking with Fox News.

Claus von Stauffenberg was a German army officer who tried to kill Adolf Hitler in July 1944.

The Republican senator from South Carolina appealed to the Russian people to "step up to the plate."

"The only people who can fix this are the Russian people. Easy to say, hard to do. Unless you want to live in darkness for the rest of your life, be isolated from the rest of the world in abject poverty, and live in darkness you need to step up to the plate," he wrote.

Russia's war on Ukraine, which began on Feb. 24, has been met with international outrage, with the European Union, United States and United Kingdom among others implementing tough financial sanctions on Moscow.

According to United Nations figures, 227 civilians have been killed and 525 injured in Ukraine since the start of the war. Ukrainian authorities, however, put the death toll at over 2,000.

More than 1 million people have fled Ukraine to neighboring countries, according to the U.N. Refugee Agency.