Former heavyweight champions Vitali Klitschko and his brother, Wladimir, are ready to take up arms in the war in Ukraine.

Vitali Klitschko, the mayor of Ukraine’s capital, Kyiv, said Thursday he plans to fight against Russia’s invasion, which began in the day’s early hours.

“It’s already a bloody war,” Klitschko said on ITV’s “Good Morning Britain.” “I don’t have another choice. I have to do that. I would fight.”

The 50-year-old Klitschko, who became mayor in 2014, was a leading figure in protests against closer ties with Russia. He also is the head of the Kyiv City State Administration.

Klitschko, a Hall of Fame boxer, now has been called to defend Ukraine and Kyiv again, along with his brother Wladimir, also a former heavyweight champion and Hall of Famer.

Wladimir, 45, enlisted in Ukraine’s reserve army in Kyiv this month as Russia began threatening an invasion.

“Now, the Russian president [Vladimir Putin] is using war rhetoric … he makes it clear that he wants to destroy the Ukrainian state and the sovereignty of its people,” Wladimir Klitschko wrote on Linkedin on Thursday. “Words are followed by missiles and tanks. Destruction and death come upon us. … We will defend ourselves with all our might and fight for freedom and democracy.”

Many other Ukrainians have been called to fight, too, as the country has begun calling up military reservists aged 18-60 for service of up to one year following a decree issued by President Volodymyr Zelenskiy.

The Klitschkos aren’t the only professional boxers affected by the Russians invasion of Ukraine.

Vasiliy Lomachenko, a two-time Olympic gold medalist and three-division champion, fled Ukraine for Greece.

Heavyweight champion Oleksandr Usyk, who defeated Anthony Joshua in September, was in London this week for a meeting related to an upcoming boxing video game but was back in Ukraine on Thursday.

“Some wrote to me that I ran away; I didn’t, I was at work but I’m back, I’m home,” Usyk said in an Instagram video in comments translated from Russian. “Friends, we have to unite because it’s a hard time right now and I’m really emotional and worry about my country, and our people. Friends, we have to stop this war; all of us together.”

Viktor Postol, who fights Saturday in Las Vegas against Gary Antuanne Russell, wanted to just focus on his fight and not the war and heavy fighting going on in Ukraine.

“The situation in Ukraine escalated a lot last couple of days, it’s hard not to think about it, but I try to focus on the fight and not for the news,” Postol, a former 140-pound champion, said at Thursday’s news conference to promote the Showtime fight. “My family is there in the middle of everything. But I am going to have my people there and my family is safe.”

It’s not just pugilists fighting back.

Alex Len and Sviatoslav Mykhailiuk, Ukranian NBA players, condemned the Russian invasion in a statement posted to Twitter on Thursday.

“A great tragedy befell our dear homeland Ukraine,” Mykhailiuk’s and Len’s statement read. “We categorically condemn the war. Ukraine is a peaceful, sovereign state inhabited by people who want to decide their own destiny. We pray for our families, friends, relatives and all the people who are in the territory of Ukraine.

“We hope for an end to this terrible war as soon as possible. Dear fellow Ukrainians, hold on! Our strength is in unity! We are with you!”