Fierce disputes between Japan and the PRC over the territorial affiliation of the Senkaku group of islands (in Chinese Diaoyu). Chinese authorities began to show interest in the archipelago in the 70s of the last century, when scientists discovered large oil deposits in this part of the East China Sea. China claims that these territories were discovered by the Chinese, while Japan got them in accordance with the disputed PRC Shimonoseki Treaty (1895).

As a result of World War II, Japan lost significant territories, including Senkaku, placed under the US protectorate as part of the Nansei archipelago. In 1972, a document was signed between the countries, according to which Okinawa and a number of islands were returned to Japan. The Nansei Archipelago, according to the agreement joined Japan.

The territorial dispute around this archipelago between Japan and China escalated after Tokyo announced in September 2012 that it had purchased the islands from private owners. After that, mass anti-Japanese demonstrations took place in the PRC. Since then, Chinese ships are almost always located near the disputed islands and periodically make demonstrative calls to the coastal zone.

Shortly after these events, on the island of Ishigaki, located in 110 km from Senkaku, a Japanese military base was built, which became a kind of advanced outpost of the Japanese Self-Defense Forces in a possible war with China.

In turn, China is building a large military base on the Nanji Islands in Zhejiang Province, located in 300 km from the disputed islands. The Chinese leadership explained that the creation of such a military base would increase the combat readiness of China in the event of a military crisis in the region.

However, it is worth noting that the situation around the islands is complicated by the fact that the United States supports Japan in its territorial disputes with its neighbors. Washington has always emphasized that it maintains the sovereignty of Japan over the mentioned archipelago, and since Senkaku Islands are the territory under the control of Japan, then they are subject to obligations under Article 5 of the US-Japan Treaty on Mutual Cooperation and Security. Therefore, in the event of an attack on the islands of the PRC, Washington is ready to defend them. Thus, the United States is currently patrolling the region under the pretext of providing free navigation.

Moreover, Washington and Tokyo regularly conduct joint military drills in the area of ​​the Senkaku Islands, working out joint actions in case of protection of the islands. It is also worth recalling that at the beginning of 2019, the United States and Japan developed a joint response plan to China's threats at the Senkaku Islands, which outlines the actions of the Japanese Self-Defense Forces and the US Armed Forces in situations that the Japanese coast guard is unable to cope on their own.

The result of all these actions was the deterioration of relations between Tokyo and Beijing, as well as the growth of anti-Japanese sentiment in China. US intervention in Sino-Japanese relations does not contribute to creating a calm atmosphere in the region and leads to a weakening of security.