The finding comes in a 2014 report that concluded Russia was in violation of the Intermediate-Range Nuclear Forces Treaty, which barred it from possessing, producing or flight-testing such cruise missiles with a range of 500 to 5,500 kilometres, the official told AFP.
President Barack Obama has sent a letter to his counterpart Vladimir Putin on the subject, which the administration official described as "a very serious matter which we have attempted to address with Russia for some time now."
"The United States is committed to the viability of the INF Treaty," the official said. "We encourage Russia to return to compliance with its obligations under the treaty and to eliminate any prohibited items in a verifiable manner."
The Intermediate-Range Nuclear Forces Treaty (INF), signed by then US president Ronald Reagan and his Russian counterpart Mikhail Gorbachev, eliminated nuclear and conventional intermediate range ground-launched ballistic and cruise missiles.
The announcement of the determination, first reported by The New York Times, comes as a time of heightened tensions between Washington and the Kremlin over Ukraine.
"Moreover, this treaty contributes to the security of our allies and to regional security in Europe and in the Far East," the official added.
In January, State Department spokeswoman Jen Psaki said Washington had raised concerns with Moscow following a Times report that it had begun testing a new ground-launched cruise missile as early as 2008, and that the State Department's senior arms control official had repeatedly raised the issue with Moscow since May 2013.
