Kharkiv, Ukraine (CNN) -- An "anti-terrorist operation" is under way in Ukraine's eastern Donetsk region against pro-Russia protesters, Kiev declared on Tuesday, with armored personnel carriers seen on the road in the restive area.
Twenty-four hours after a Ukrainian ultimatum expired for the protesters to lay down their arms, acting President Oleksandr Turchynov told Parliament the operation would be "conducted step by step, responsibly, cautiously.