Defense Minister Itsunori Onodera on Tuesday confirmed that the Chinese navy vessel locked a weapons-targeting radar at a Maritime Self-Defense Force ship in the East China Sea.

The Chinese Navy frigate used radar for targeting the MSDF destroyer Yudachi from around three kilometers away last week. Onodera’s statement went on to warn that the bitter territorial row could escalate “with one false step”.

“On January 30, something like fire-control radar was directed at a Japan Self-Defense Maritime escort ship in the East China Sea,” Onodera told reporters in Tokyo.

Onodera said a similar incident occurred on January 19, in which a Chinese navy ship directed fire-control radar at a Maritime Self-Defense helicopter that took off from the destroyer Onami, adding that such moves were “very abnormal” even if it only lasted minutes.

“This is an extremely unusual development, and there is the possibility of the situation moving into a very dangerous one with one false step,” Onodera said.

“We will ask the Chinese side’s self-restraint from taking such dangerous action.”

Hisao Iwashima, a Japanese defense analyst, said Beijing needed to answer for what its navy had done.

“It could have been a test but the Japanese side wouldn’t have known if it was, or it would lead to a launch,” he told AFP. “The Chinese side is responsible for explaining why it took such potentially dangerous action.”

The move could complicate efforts to diffuse tensions in the volatile waters through a possible summit between the the countries’ leaders.