VIENNA — U.S. Secretary of State Rex Tillerson is lambasting Moscow for its aggression in Ukraine ahead of a meeting with Russia's foreign minister.

Tillerson is using his opening speech at the Organization for Security and Cooperation in Europe to call out Russia for interfering with nearby countries. He says Russia is "arming, leading, training and fighting alongside anti-government forces" in Ukraine.

Tillerson says the United States will "never accept Russia's occupation and attempted annexation" of Crimea. He says sanctions will stay in place until Russia returns control of the peninsula to Ukraine. He says the U.S. joins Europe in maintaining other sanctions until Russia withdraws military forces from the Donbass region of eastern Ukraine.

Tillerson meets later Thursday in Vienna with Russian Foreign Minister Sergey Lavrov.