NATO's second-ranking official says Moscow's annexation of the Crimean Peninsula and its destabilizing actions in eastern Ukraine have compelled the U.S.-led alliance to start treating Russia as more of an enemy than a partner.

This marks a turning point in decades of effort by NATO to draw Moscow closer, says Alexander Vershbow, the deputy secretary-general of the alliance. He made the remarks to a group of reporters.

Vershbow said the alliance is considering new measures aimed at deterring Russia from any aggression against NATO member countries along its border, such as the Baltic states that were once part of the Soviet Union.

Vershbow said that among possible moves by NATO are deployment of more substantial numbers of allied combat forces to Eastern Europe, either permanently or on a rotational basis.