Watch: Former World Champion Boxers Vitali and Wladimir Klitschko Will Help Defend Ukraine Against Russia

Vitali and Wladimir Klitschko have said they plan to help defend Ukraine against Russia's invasion. Wladimir joined Ukraine's reserve army last month, and Vitali is the current mayor of the country's capital, Kyiv. Wladimir also called for Ukraine's international partners to "stay united against this aggression."