The United States has warned Russia to respect its arms control treaty obligations.
The warning came amid reports that Moscow has deployed a cruise missile unit in violation of a 1987 arms control treaty between the two countries.
State Department spokesman Mark Toner said Russia is violating INF Treaty obligations that bans ballistic missiles with a range of 500 to 5,500 kilometers.
Russian President Vladimir Putin has defended Moscow's test program, arguing that the United States is also in breach of the INF Treaty. He said new missiles are needed to maintain the balance of power.