Russia should not be allowed to continue destabilizing the situation in Ukraine, so sanctions against Russia will be preserved, U.S. Assistant Secretary of Defense for International Security Affairs Robert Karem has said.

"Russia has occupied Crimea and continues deepening the crisis in Donbas. We cannot tolerate the annexation of Ukrainian territory by Russia and cannot allow Russia to continue destabilizing the situation in Ukraine," he said at the 11th Kyiv Security Forum on Friday.

Karem paid tribute to the Ukrainian military and said: "We support the idea of a peacekeeping mission in Donbas and call for the full implementation of the Minsk agreements."

"The U.S. and its partners will continue to pressure Russia to comply with the Minsk accords. Sanctions will continue until this condition is implemented. Sanctions in connection with Crimea will also remain in effect until the annexation of the peninsula ends," the U.S. deputy defense minister said.

According to Karem, Ukraine "has done a lot" in the issue of reforming the defense sector.

"We welcome Kyiv's desire to join NATO," he added.

He also said that "collective action is the key to success in confronting [Russian] threats."