The Open Skies Treaty

The Open Skies Treaty was signed in 1992 and entered into force in 2002, with 27 of its 34 participating states having ratified¹ the treaty. The United States withdrew in November 2020, closely followed by Russia in June 2021. The treaty is a political agreement designed to enhance mutual understanding and confidence amongst state parties through unarmed aerial surveillance flights over the entire territory of each member, which are used to verify military movements and arms control treaties. Each state party is permitted to conduct short-notice and unarmed reconnaissance flights, and additional state parties are permitted to accompany and observe the mission. The sensors on board the flights are certified according to treaty stipulations prior to inclusion on the aircraft and a copy of the data collected by these sensors is supplied to the host country. All state parties receive a mission report and may purchase the data collected. This action of jointly collecting data, so that authenticity thereof is not contested, is an exceptional strength² of the treaty. The treaty upholds the following ³ on the instrumentation and data collected:

• Optical and panoramic framing cameras: Ground resolution of no better than 30 cm.

• Video cameras with real-time display: Ground resolution of no better than 30 cm.

• Infrared line-scanning devices: Ground resolution of no better than 50 cm.

• Sideways looking synthetic aperture radar: Ground resolution of no better than 3m on a single radar unit (object separation capability of 5 m). There may not be 2 radar units observing from both sides of the aircraft simultaneously.