According to the Washington Post, The violation, which began some years ago, is included in a 2014 compliance report on the treaty to be released Tuesday and was the subject of a letter President Obama sent Monday to Russian President Vladimir Putin, Censor.NET writes.
"This is a very serious matter which we have attempted to address with Russia for some time now," the official said. "We encourage Russia to return to compliance with its obligations . . . and to eliminate any prohibited items in a verifiable manner."
It was unclear how long the testing lasted, or whether it was ongoing. The official, speaking on the condition of anonymity, said that "we have notified Russia of our determination and are prepared to discuss this in a senior-level bilateral dialogue immediately."
Obama's letter to Putin was first reported online Monday by the New York Times, which said that Russia began testing the missiles in 2008 and that the State Department first raised the possibility of a violation with Russian officials in 2013. At the time, the paper said, Russia said it had looked into the matter and considered it closed.
The Intermediate-Range Nuclear Forces Treaty, signed by Presidents Ronald Reagan and Mikhail Gorbachev in 1987, prohibits possession, production or flight testing of a ground-launched cruise missile with a range of 300 to 3,400 miles, or possession or production of launchers of such missiles.
News of the alleged violation comes as relations between the United States and Russia are seriously strained over Russia's backing of separatist fighters in eastern Ukraine. Obama administration officials have said that, despite their growing differences and the imposition of U.S. economic sanctions over Ukraine, Moscow has continued to cooperate with Washington on a range of nuclear and other foreign policy issues.