The incursions happened Wednesday and Thursday in Japan's contiguous zone around Okinawa and the Senkaku Islands by a Chinese frigate and submarine presumed to be from China, Japanese officials said.
Not surprisingly, the frigate from China and likely submarine from the same nation drew consternation from Japan after sailing near the territorial waters of Japan.
Defense Minister Itsunori Onodera said the missile interceptor system Aegis Ashore, to be deployed in Japan, could be used to intercept Chinese cruise missiles, a statement that may not be well received in Beijing.
"The [Diaoyu Islands] are a natural part of Chinese territory", Lu Kang, Beijing's foreign ministry spokesman, said Thursday, according to UPI. Of course, not neglecting the pro-Han Chinese demographic reality in relation to undermining the indigenous of Tibet and Xinjiang - and China's containment policy of democratic Taiwan. "This unilaterally heightens tensions", Onodera told reporters. Just $5 a month.
The incident came as Japan is pushing to host a trilateral summit with leaders from China and South Korea. Officials from both sides met in Shanghai for two days and chose to implement the hotline.
"We are monitoring the vessels and sending a message to them that they entered the contiguous waters near Japanese territory", said Yamaguchi. It does not include the contiguous zone, where a coastal state is afforded some law enforcement rights under worldwide law.
The crisis management mechanism, however, excludes Japan's territorial waters and air space around the disputed Senkaku Islands. The submarine left the zone on Thursday morning, but again sailed into the zone northeast of Taisho Island in the Japanese-administered Senkaku chain later. On Thursday, Japan issued a warning to China to stand down after a military warship and submarine were seen near the disputed waters in East China Sea.
The Chinese Foreign Ministry retorted by asking Japan to "stop making trouble over the Diaoyu Islands issue and to meet China halfway in accordance with the four principles agreed by both sides in 2014", a spokesman said, referring to a consensus on their differing stances reached by the two countries several years ago. A submarine adds to this growing list.