NATO's secretary-general said Russia has shown no signs of complying with a key Cold War-era arms-control treaty, amid years of accusations from Washington and European allies.
Moscow has repeatedly denied Western allegations that it has deployed ground-launched cruise missile systems in violation of the 1987 Intermediate-Range Nuclear Forces (INF) treaty.
Earlier this year, the United States gave formal notice that it would withdraw from the pact as of August 2, if Russia does not begin destroying the missiles in question.
Speaking on July 5 after talks with Russian diplomats, NATO chief Jens Stoltenberg said there were still no signs of Moscow trying to comply with the treaty.
"We didn't see any sign of Russia being willing to come back into compliance," he said. "And time is running out."
Known as the INF, the treaty was a landmark agreement that eliminated an entire class of missiles that were deployed in Europe and western Russia.
The missiles were considered destabilizing because of their short flight time, meaning they could hit targets with a nuclear strike with little or no notice.
Stoltenberg called Russia's breach of the treaty "serious" and said it required a firm response.
"If we accept that the INF treaty is violated with impunity, with zero consequences, then we undermine the trust and the credibility of all other arms-control agreements," he said.
Earlier this week, Russian President Vladimir Putin signed legislation formally suspending Russia's participation in the treaty.
Following talks with Stoltenberg, Russia said it would not deploy mid-range nuclear missiles in Europe, as long as the United States does not do so first.
"We do not intend to deploy such weapons in Europe and other regions where U.S. short- and medium-range missiles have not and will not be deployed," Russia's mission to NATO said in a statement.