Former heavyweight boxing champion Wladimir Klitschko enlisted in Ukraine's reserve army in Kyiv on Wednesday, saying that love for his country compelled him to defend it.
Ukraine has been bracing for a possible military offensive after Russia assembled tens of thousands of troops near Ukraine's borders in recent weeks, though Moscow says it has no plans to invade.
Both Wladimir Klitschko, 45, and his brother Vitali Klitschko, the mayor of Kyiv and also a former heavyweight boxing champion, were present during the opening of a Territorial Defense Forces recruitment centre in the capital.
"One district from here, my little girl is going to school. The school is currently closed because the ambassadors have sent the families home," Wladimir Klitschko said, referring to a partial drawdown by some embassies.
"It is the love, the love for my city, my home, my family, my neighbours, my daughter that has brought me here today, that I took this initiative and am now taking part in this territorial defense."
A diplomatic solution to the conflict with Russia is preferred, according to Vitali Klitschko. "If not, we have to prepare to take weapons in our hands, and defend the country," he added.
Ukraine has pressed Western allies to send aid and weapons in order to deter Russia from attacking.
Both brothers spent part of their boxing careers in Germany. Last week, Vitali Klitschko joined a chorus of Ukrainian criticism against Berlin, which has refused to supply weapons. But on Wednesday, Wladimir Klitschko was more emollient.
"I would say I am grateful to Germany, because no other country -- we are always very critical -- has invested into Ukraine as much as Germany has in the past few years," he said, speaking in German.
"Germany is the number one, and then all the other countries that supported us. I want to say 'thank you' for this support."