The Chinese and Russian militaries carried out a joint strategic aerial patrol in the relevant airspace of the Sea of Japan, the Ministry of National Defense announced on Friday.

The patrol was part of the annual cooperation plan between the two militaries, the ministry said in an online release.

READ MORE: Powering up China's 'flying shark' J-15 carrier-based fighters

According to the ministry, the joint patrol was the ninth between the two militaries since 2019. Senior Colonel Wu Qian, the ministry spokesman, said at a previous news conference that such exercises aim "to test and improve the collaboration between the air forces of the two countries and promote strategic mutual trust and pragmatic cooperation of the two militaries".

ALSO READ: China's first female carrier aircraft pilots debut at Airshow China

Xu Nuo contributed to this story.