The Russian Duma approved the Open Skies Treaty on April 18 by a vote of 281-103, moving it closer to entry into force. The treaty still must be approved by the upper house of the Russian parliament, the Federation Council, and by President Vladimir Putin. But passage by the Duma, the lower and more powerful Russian legislative body, stood as the major test for Russian ratification. Belarus, which has said it would act once Russia did, must also ratify the treaty before it can enter into force.
Signed in March 1992 between the members of NATO and the former Warsaw Pact, the Open Skies Treaty permits states-parties to conduct unarmed reconnaissance flights over the entire territory of other states-parties to collect data on their military activities and weaponry. Open Skies aircraft may be equipped with cameras, infrared sensors, and other equipment that could allow observing parties to distinguish between tanks and trucks. Parties conducting overflights must provide at least 72-hours notice and supply a mission plan 24 hours in advance.
Based roughly on the size of each country's territory, every state-party is assigned a passive quota, the maximum number of flights it must allow annually over its own territory, and an active quota, the maximum number of total flights per year it may conduct over other states-parties. The United States, which ratified the treaty in December 1993, and Russia have passive quotas of 42, the highest of all states-parties.
All countries with a passive quota of eight or greater must ratify the treaty before it can enter into force. Thus, Belarus, which shares Russia's passive quota, must also ratify the treaty to trigger its entry into force. Except for Russia, Belarus, and Kyrgyzstan, all of the other 27 treaty signatories have completed ratification.
Russia's delay in ratification has been attributed to several factors, including cost, which Moscow has increased by insisting that overflights of its territory be conducted in Russian planes rather than observing countries' aircraft.
While awaiting entry into force, treaty signatories, including Russia, have conducted joint trial flights. Since 1993, the United States has participated in 76 such flights.