Russian troops could begin fighting for Ukraine in coming days

The next phase of the Russian military campaign in Ukraine could begin in the next few days, according to two senior U.S. defense officials. Ukraine is rapidly running through artillery and artillery rounds.

The Russian military could begin moving some of its troops back into Ukraine as soon as this weekend or early next week, according to officials.

Russian troops retreated from Kyiv and northern Ukraine about two weeks ago, moving north into Belarus and Russia.

At the time, U.S. officials assessed the Russians intended to re-group and then begin another invasion, focusing on the Donbas region and southeastern Ukraine.

A senior defense official said that Russian officials believe Russia may move troops back into Ukraine and start the offensive before all Russian troops are ready to fight again.

Russia and Ukraine have fought each other in the east and south, even as the Russian military prepares for the next phase of the invasion.

A senior defense official said that the Ukrainian military has been spending several thousand artillery shells every single day during that time.

The Biden administration announced this week that it was sending 40,000 artillery rounds andmm howitzers to Ukraine. The Ukrainian military uses thousands of dollars a day, but that 40,000 will only last a little over a week, the official said. U.S. officials are trying to convince allies to send more artillery and ammunition to Ukraine so it doesn't run out when the offensive ramps up.

Russian troops are likely to try to encircle Ukrainian troops arrayed along the border between Donbas and the rest of Ukraine in this coming offensive - a military move called a double envelopement. The Russian military relied heavily on long-range fire - cruise missiles, long-range artillery, airstrikes - in the early weeks of its attack on Ukraine, but the main weapons of this new offensive will likely be artillery and short-range missiles, a senior defense official said.

The Ukrainian military has some artillery but most of it is outdated, much is beaten up, and some has been destroyed by the Russians. The newer howitzers from the U.S. will be more durable than the existing Ukrainian artillery, but the world has to supply Ukraine with munitions so it can stay in the fight.

The Russians have already begun shaping operations in the southeast, preparing the area around Donbas for a Russian ground invasion, according to a senior defense official. On Thursday, a senior defense official said Russia has begun moving equipment into western Russia in preparation for the offensive, including helicopters that are now staged for insertion into Ukraine.