US Deputy Secretary of State Wendy Sherman has warned Russia that it must choose between diplomacy or confrontation with the West.
Sherman spoke following negotiations between NATO and Russia, one of three diplomatic events this week aimed at easing tensions over Ukraine.
Russian Deputy Foreign Minister Alexander Grushko said that NATO might not specify Moscow’s security demands, which include Ukraine not joining NATO.
Russia has massed some 100,000 troops near the Ukrainian border, raising fears of an invasion.
Sherman reiterated that the United States, and other NATO members, would never agree to veto Ukraine’s admission to NATO, noting that the military alliance has an open door policy.
Ukraine’s constitution contains a clause requiring it to seek membership in NATO.
But she said there were areas where progress might be made, and that Russia had to decide what it wanted to happen next.
“Russia, in the first place, has to decide whether it’s really a question of security, in which case they have to negotiate, or whether this is all a pretext for something else. Maybe they don’t know yet,” she added.
She added that the United States and NATO are preparing for all possibilities.
Russia has issued a series of demands aimed at preventing NATO from expanding eastward, as well as reducing the alliance’s presence near its borders.
NATO categorically rejected these demands, but said it was ready to talk regarding other issues, including arms control and the limits of military exercises.
NATO is an alliance of 30 countries that was founded in 1949.
After Wednesday’s talks in Brussels, Grushko warned that a further deterioration in relations might lead to unpredictable consequences for European security.
His warning echoed the words of NATO Secretary-General Jens Stoltenberg, who said there was “a real danger of a new armed conflict in Europe”.
In 2014, Russia annexed Crimea, following the Ukrainians ousted their pro-Russian president.
Later that year, Russian-backed separatists took control of large parts of eastern Ukraine.
Russia insists there is nothing to fear a recent build-up of forces. But Russian President Vladimir Putin spoke of “technical military measures” if the West’s “aggressive” approach continues.
Thursday’s talks will take place at the Organization for Security and Cooperation in Europe in Vienna, the first time this week that Ukraine has a seat at the table.