Ukraine says Russia's offensive in Donbas has begun. Here's what ...

Ukrainian soldiers stand on an armored personnel carrier not far from the front line with Russian troops in Izyum district, Kharkiv region, on Monday.Ukrainians had been expecting a renewed Russian offensive in the eastern region known as the Donbas, and now Ukraine's president says it's underway.President Volodymyr Zelenskyy said in his evening address that Russian forces have begun their new offensive against cities in the east and south, adding that a "substantial part" of the Russian army is now taking part in the military operation."Today we can already say that Russian armed forces have begun the assault on the Donbas, which it has been preparing for," Zelenskyy said.A senior U.S. defense official said on Tuesday that Russia is conducting "limited offensive operations" southwest of Donetsk and south of Izium, which are a "prelude to larger offensive operations."The Donbas region in eastern Ukraine along the border with Russia has long been of interest to the Kremlin.In 2014, after antigovernment protests broke out across Ukraine, two breakaway regions in Donbas formed under the control of Russian-backed separatists: the Luhansk People's Republic and the Donetsk People's Republic.Those two regions comprised parts of the larger Luhansk and Donetsk provinces that make up the Donbas.