A group of Russian military observers begin on Monday a six-day inspection mission in the skies of Latvia and Estonia under the Open Skies Treaty, the Defense Ministry’s press office reported.

The flights will be conducted on September 10-15 from the Latvia’s Riga and Estonia’s Tartu airports. The maximum flight range will total about 1,600 km (some 1,000 miles) under the agreed flight routes.

“Aboard the An-30B aircraft, Russian specialists will exercise control together with their colleagues over the procedure of the use of surveillance system equipment and compliance with existing accords,” the press office said.

The Open Skies Treaty, signed in 1992 at the initiative of U.S. President George H.W. Bush, established a regime of unarmed aerial observation flights over the territories of its 34 member states to promote openness and the transparency of military forces and activities.

The treaty entered into force on January 1, 2002 and its regime covers the national territories (land, islands, and internal and territorial waters) of all the treaty signatory states. It is an important element of the European security structure.