MOSCOW (AP) — NATO's chief has lauded Ukraine's weaponry pullback in the east but has also called upon Russia to step up efforts to bring peace to the war-torn region.

NATO Secretary General Jens Stoltenberg told reporters Wednesday at the Black Sea port of Odessa that NATO welcomes Ukraine's efforts to pull back heavy weapons in the east, the final hurdle before much-anticipated peace talks between the leaders of Ukraine, Russia, France and Germany. The talks aim to put an end to a deadly conflict between government troops and Russia-backed separatists.

Stoltenberg, who visited four NATO vessels that stopped by Odessa during their Black Sea patrol, also said Russia has a "special responsibility" in the conflict and urged Moscow to "withdraw all their troops and their officers" from the area.

Russia has denied sending in troops to support the separatists.