All this Japan/China military tension is very strange as it remembers the Cold War.
It´s still more strange because those countries have strong commercial relations.
It´s like if a guy (japan) had sold me (China) a car or a computer, for example, and then, when i start to walk near his address, he starts to follow me showing his gun and asking me what are my intentions to be walking near his address.
So that, to sell me a car or a computer, i was good enough to him, but for me to bypass near his (the seller) address, i am an armed suspect with suspected aggressive intentions.
That don´t make sense at all.
Edited.
I know that China did siege a US survaillance ship and protested it´s presence in their EEZ waters, but the US ship was there deliberately with the purpose of survaillance, while the
Chinese fleet had to pass the japanese Islands because the Islands are in their way to the Pacifc Ocean, so that was not a deliberate action against Japan, just a bypass.
US-Japan military alliance, together with South Korea, Taiwan, the Philippines, people called they are the Asia-Pacific NATO, from the map, they form an island chain, surrounded by sea to China.
Although the Cold War has pasted, but the United States in order to maintain hegemony in the Asia Pacific region, continue to carry out strategic encirclement of China, because China is a rise of large country, not only that, but also into the strict arms embargo on China.
Japan's past aggression against China, but it has not learned the lessons of failure. Instead, using the US-Japan military alliance, to seek the interests of the East China Sea, For example, the Diaoyutai islands, the Japanese attempt to encroach upon, so that it can be invaded and occupied large areas of the territorial sea and the exclusive economic zone.
While Japan and China have close commercial relations, but on the other hand, the winning marine resources, are equally important.Although both sides not going to military conflict, but both sides have made prevention.