The U.S. and Japan reacted sharply to China's establishment of an East China Sea Air Defense Identification Zone (ADIZ). On Tuesday, two U.S. B-52 bombers entered the zone without informing Chinese authorities.

To truly understand what has happened, we need to think about it clearly.

First of all, we should understand the aim of setting up an ADIZ. Normally, when a foreign aircraft has already entered a country's air territory, it is too late for the country to react to it. Setting up an ADIZ above the open sea will give a country sufficient time to identify the aim of the mission and make an appropriate reaction.

It is not necessary to become nervous every time a foreign aircraft appears in a country's ADIZ. During times of peace, a country will not pay much attention to foreign aircraft flying in its zone without advance notice as long as it does not consider the aircraft a threat.

There are no specific rules about where to set up an ADIZ, like how far the zone should be away from a country's territorial water or if its boundary should be parallel to the country's territorial sea baseline. This depends on the country's real needs and capability.

The U.S. said that the B-52 flights into China's ADIZ were a military exercise targeting North Korea, in which case, the two bombers should have flown to the destination directly from Guam. However, they chose a totally different route. After entering the ADIZ, they turned right, kept to the zone's boundary and then flew northward to North Korea.

This at least tells us two things. First, the U.S. has actually accepted the existence of China's ADIZ. Otherwise, the two bombers would not have chosen such a bizarre route. Second, since China didn't react to the flight, the U.S. probably will make more attempts until it discovers China's bottom line.

The U.S. government's comments on this incident also left us a lot to think about. According to the U.S, the flight was not only a warning to Beijing but to Tokyo as well. Taking into account the two bombers' bizarre route, the U.S. was trying to caution Japan against hasty action and to encourage it to leave the issue to the U.S.

However, this reminds us of what the U.S. did to the Nationalist troops after they fled to Taiwan in 1949. In 1958, the Chinese People's Liberation Army attacked the Nationalist troops at Kinmen and the U.S. promised to protect them. But during the battle, the U.S. frigates actually abandoned the Nationalist naval vessels because of the strength of the attack.

In view of this, it would be better for Shinzo Abe not to risk relying on the U.S. to saving Japan's face.

The author is a military commentator.

The article was translated by Chen Xia. Its original unabridged version was published in Chinese

Opinion articles reflect the views of their authors, not necessarily those of China.org.cn.