Priozersk is a closed city located on the northern shores of Lake Balkhash, Kazakhstan.

It serves as the administrative center of Sary Shagan anti-ballistic missile testing site.

Tens of thousands of workers and hundreds of missile experts and army officers arrived after the Soviet government decided to establish a secret military base in the Kazakh Steppe.

After the Soviet Union's collapse, the Russian Federation agreed with Kazakhstan to lease some military units for 50 years.

The Russian Army continues to use the base at Priozersk as the testing site for improving anti-ballistic and anti-aircraft defense systems.