Ukraine appears to have at last followed through on its threats to use military force against separatists in the east. Heavy gunfire rang out inside Kramatorsk air base today, Sky News reports. Interim Ukrainian President Oleksander Turchinov announced that Ukrainian troops had retaken the base, driving out the pro-Russian militiamen who had been holding it, the AP reports. Russian state-controlled TV is reporting that 11 were killed in the fighting. Earlier, separatists voluntarily surrendered a police headquarters in the same town. It was the first military action since separatists ignored Kiev's deadline to clear out, which passed more than 24 hours ago.
Earlier today, Turchinov had announced that "anti-terrorist operations" had begun, but would unfold "in a considered way." Ukrainian tanks have also been spotted less than 44 miles from Slovyansk, a city under tight insurgent control, the AP reports. Separatist checkpoints have sprung up all along roads leading into the city—there was even a Russian flag flying at one of them. Russia condemned the attack. "I will be brief: Ukraine is on the brink of civil war," Dmitry Medvedev said. "It's frightening." (Read more Ukraine stories.)