The US recently blocked a new Russian Tu-214ON plane from conducting surveillance flights over other countries as part of a Treaty on Open Skies. This is despite 22 signatories to the pact confirming that the aircraft complies with all the requirements. We examine the legal ways Russia, the US and others can monitor each other. The 'mutual monitoring' concept, initially proposed by US president, Dwight Eisenhower, was intended to allow each country to verify compliance with existing and future arms control treaties. However, the Soviet leader, Nikita Khrushchev, rejected the idea, which surfaced at the height of the Cold War. Shortly before the fall of the Soviet Union, George H.W. Bush revived the framework that would promote “greater openness and transparency” on military matters and help to build trust between NATO and the Warsaw Pact countries. The Open Skies Treaty was signed in Helsinki in 1992 and ratified by 34 countries. The agreement states that member countries are permitte