Russia’s President Vladimir Putin and his Belarusian counterpart have watched a massive joint military exercise of the two ex-Soviet neighbors that involved more than 22,000 troops.

The West 2013 exercise conducted Thursday near the city of Grodno in western Belarus and in Russia’s westernmost Kaliningrad region also involved more than 500 armored vehicles and about 90 aircraft along with ships of Russia’s Black Sea Fleet.

The two armies have regularly conducted joint maneuvers, Thursday’s exercise being the biggest so far.

Belarusian President Alexander Lukashenko attended the exercise along with his nine-year old son, who donned full combat fatigues.