The intrusion into Japanese airspace "is not only a serious violation of our territorial rights but also a security threat", says spokesperson Yoshimasa Hayashi on Tuesday.
China's growing and military influence in the Pacific region and the territorial disputes it has with, among others, the Philippines, has got the US and its allies to see red.
From China, it is announced that information about the situation is being gathered.
I want to emphasize here that China has no intention of intruding into any country's territorial airspace, says Foreign Ministry spokesperson Lin Jian.
Analysts believe that China is probing Japan's air defense network in search of intelligence as Tokyo expands its defense cooperation with the US and other countries in the region.
