Russia launched a massive attack on Ukraine's Kharkiv, killing four and injuring dozens. President Zelenskyy condemned the violence and appealed for urgent air defense assistance.

The threat from drones to military isn’t just overseas. Last year, the military tallied 350 drone incursions on domestic bases, according to U.S. Northern Command.

“It’s an eyebrow-raising moment,” Gen. David Allvin, the US Air Force chief of staff, said at a defense conference in Washington on Tuesday, adding that the US is vulnerable to similar attacks.