The United States has long suspected Russia of violating the INF treaty prohibiting the deployment of nuclear and conventional ground-launched ballistic and cruise missiles with intermediate ranges, defined as 500-5,500 kilometers (310-3,410 miles). Of particular concern has been Russia's development of the R-500 ground-based cruise missile, as well as the testing of the SS-27 Mod 2 intercontinental ballistic missile at ranges prohibited by the INF treaty. Over the past few years, the United States has launched inquiries into these alleged breaches and has indicated that it views them as serious violations of the INF treaty. At the same time, Russia also believes the United States has violated the treaty. Specifically, it points to the development of armed unmanned aerial vehicles that it claims could be used as cruise missiles.