The Obama administration says Russia has violated a 1987 nuclear pact by testing a ground-launched cruise missile.
An administration official called the matter "very serious" and says the U.S. is "prepared to discuss this in a senior-level bilateral dialogue immediately." The New York Times reports that President Obama notified Russian President Vladimir Putin of the finding in a letter Monday.
The Intermediate-Range Nuclear Forces (INF) Treaty bans the possession, production or flight-test of a ground-launched cruise missile with a range capability of 500 to 5,500 kilometers. Russia has reportedly been testing the missiles for years, beginning in 2008, but the matter has only recently been taken up by top U.S. officials. It comes as the relationship between the two nations has strained over the crisis in Ukraine.
The Times notes that the INF Treaty, signed by Ronald Reagan and Mikhail Gorbachev in 1987, "helped seal the end of the Cold War and has been regarded as a cornerstone of American-Russian arms control efforts."