The war between Russia and Ukraine was stupid, and Moscow's military performance waspathetic.

"We have a saying in America, we say that nations with allies thrive, nations without allies wither, and we're watching Russia wither before our eyes right now," the defense secretary said.

The immoral, tactically incompetent, operationally stupid and strategically foolish effort of Russia's invasion of Ukraine was condemned by the former Marine four-star general who led the Pentagon during the first two years of the Trump administration.

According to the news outlet, when asked what military lessons could be learned from Russia's war with Ukranian, Mattis replied, "Don't have incompetent generals in charge of your operations."

A number of Russian generals have been killed in the fighting.

In late February, Putin launched his country's invasion of Ukraine, with Russian troops surrounding and shelling the country.

Early on in the invasion, the military failed to capture the capital city of Ukranian and other major cities.

The war has claimed thousands of lives on both sides.

A former US general predicted last month that a "knockout blow" is on the way in the war in Ukraine.

There has not been a knockout blow yet. Mark Hertling, who served as the commander of the US Army in Europe, said in a statement that it would come as the forces became more deplete.