MOSCOW (AP) — Russian President Vladimir Putin on Saturday ordered military forces in central Russia on combat alert as well as a drill of airborne troops, a day after Ukraine ordered a cease-fire with pro-Russian rebels.

NATO said earlier this week that Russia has resumed a military build-up on the border with Ukraine where pro-Russian separatists have been fighting government forces for weeks in a conflict that has left about 300 people dead and displaced over 34,000.