The Chinese military sent naval and air forces for “joint combat readiness patrols” in the waters and airspace of the East China Sea on Saturday, a day after a Japanese warship transited the Taiwan Strait.

The exercises were “a routine arrangement organized in accordance with the annual plan, aiming at testing the joint operations capabilities,” Senior Col. Xu Chenghua, a spokesperson for the Chinese military’s Eastern Theater Command, said in a statement. 

Xu said the Eastern Theater Command “will routinely organize relevant military operations based on the need of the security situation, and safeguard state sovereignty and security as well as regional peace and stability.”