Monday saw Russian warships depart for China to participate in joint naval drills. This exercise demonstrates the close defense ties between China and Russia as the two countries face increasing tensions with the United States.

According to the Russian Defense Ministry, the Varyag missile cruiser and the Marshal Shaposhnikov destroyer as well as two corvettes from Russia’s Pacific Fleet will participate in maneuvers in East China Sea beginning Wednesday.

According to the ministry, the Chinese navy would deploy several surface warships as well as a submarine for this exercise. According to the ministry, the drills will also include Russian and Chinese aircraft.

In recent months, Moscow and Beijing have shown increasing military cooperation.

Joint patrols were conducted by the Russian and Chinese H-6K bombers and Tu-95 bombers of both the Russian and Chinese air forces over the Sea of Japan, East China Sea and Sea of Japan in November. The drills saw the Russian bombers landing in China for the very first time and the Chinese bombers flying to an Russian airbase.

China sent over 2,000 troops, along with 300 military vehicles, 21 combat planes, and three warships, to participate in a joint exercise with Russia in September. These maneuvers were the first time China had sent troops from all three branches of its military in order to participate in a Russian drill. It was also a demonstration of China’s mutual trust.

Since the February 24th invasion of Ukraine by Russian President Vladimir Putin, defense cooperation between Moscow-China has been stronger.

China, which declared a “no limits friendship” with Russia, has refused to criticize Moscow’s actions and blamed NATO and the U.S. for provocation. It has also criticized the harsh sanctions imposed upon Russia.

Russia has supported China in the face of tensions between the U.S. and China over Taiwan.