Ukraine says it is launching counteroffensive; Russia’s PM says nation on brink of civil war

DONETSK, Ukraine— The Ukrainian government announced the start of a staged counteroffensive Tuesday to reclaim control of the eastern part of the country, as Russian Prime Minister Dmitry Medvedev warned that Ukraine was descending into civil war.
  
Facing mounting pressure to act following the takeover of official buildings by pro-Russian separatists in at least nine cities in the restive east, acting Ukrainian President Oleksandr Turchynov said that a counterterrorism operation had begun in the northern Donetsk region early Tuesday.
Eyewitnesses and officials reported a buildup of Ukrainian forces not far from Izyum, a city located near the border of Kharkiv and Donetsk provinces in the east. The area sits a few dozen miles north of Slavyansk, which was seized by well-armed pro-Russian activists Saturday and was the site of a failed operation by Ukraine to reclaim the city on Sunday.
An Izyum official involved in the mobilization and who asked not to be named said the city was being used as a fueling and feeding station for Ukrainian troops, who had begun arriving over the weekend and were taking up positions outside the city’s limits.