Russian President Vladimir Putin and his Chinese counterpart, Hu Jintao, have attended a joint military exercise in the Ural Mountains in Russia.
The exercise involved 6,000 troops from Russia and China.
They were joined by troops from the other four nations of the Shanghai Co-operation Organisation - Kazakhstan, Uzbekistan, Tajikistan and Kyrgyzstan.
It is the first time that such manoeuvres have taken place on Russian territory.
Troops used a joint air and land assault to attack a mock town.
In the exercise scenario, the town was being held by terrorists.
Fighter jets joined in with the assault.
Correspondents say the exercises highlight the growing strategic importance of energy-rich Central Asia, which faces a host of security threats.