The latest China-Japan incident took place “in the sea southeast of the Sakishima island chain,” Reuters reports.

Japanese Defence Minister Itsunori Onodera said Japan “carried out the usual precautionary observations in accordance with international law.”

Onodera didn’t dispute China’s desire to carry out drills, according to Reuters.

“For China to carry out regular drills is not illegal, and for us to be cautious is also natural, I believe,” he said.

“It’s important to set up a Japan-China hot line so suspicion and mistrust doesn’t arise between the two sides.”