Kurt Volker, former U.S. envoy to Ukraine, said on Sunday that the Russian invasion will not end through negotiations, adding that Russian President Vladimir Putin is “bent” on destroying the country.

“Face the Nation” host Margaret Brennan asked Volker on CBS if he could see any countries being able to negotiate an end to Russia’s attack on Ukraine.

“Not at all. No, we have to understand that Putin is bent on a military victory. He wants to destroy Ukraine, decapitate the leadership. He doesn’t care about how many casualties this causes, what happens to the civilian population. This is a messianic mission that he is on. This is why he has to be stopped,” said Volker.

Volker also called for the U.S. to provide A-10 aircraft to Ukraine, noting that Ukrainian pilots are trained to use the jets.

Brennan noted that numerous other nations including France, Germany and Israel have attempted to diplomatically stop the war, and asked Volker who would be able to bring about an end.

“Ukrainian people can do this,” Volker said. “Ukrainian people are there, they are determined, they are fighting. We are fortunate that we don’t have to be in a position of fighting Putin or trying to stop him. The Ukrainian people are ready to do this. And that’s why it’s critical that we give them every bit of support and assistance we can.”