• This is the first time that both the navies were passing through the strait
  • Analysts called the act a "calculated maneuver" by Beijing and Moscow
  • Japan had limited its territorial waters in Tsugaru to just 3 nautical miles 

For the first time in history, 10 warships belonging to China and Russia passed through Tsugaru Strait, a narrow chokepoint in the north of Japan, setting off alarm bells in Tokyo. 

The vessels sailed together eastwards to the Pacific Ocean and are said to be a part of "Naval Interaction 2021," a joint maritime exercise planned by the Russian and Chinese navies this month, reported Japan Today.

Tokyo's Defense Ministry said it first identified the ships Monday morning, around 110 km southwest of Okushiri Island, on the west side of Hokkaido. 

The Tsugaru Strait is a narrow chokepoint connecting the Sea of Japan with the Pacific Ocean, with its narrowest point only 18.7 kilometers wide. 

However, it is considered an international waterway due to Japan's Cold War-era decision to allow U.S. ships carrying nuclear weapons to pass through without violating its non-nuclear position. Japan had then limited its territorial waters to just 3 nautical miles from shore, as opposed to the customary 12. 

Since then, the narrow strait is used for international navigation, and the passage of foreign ships is not considered unlawful. 

However, analysts are calling the act a "calculated maneuver" by Beijing and Moscow and said the passage of warships did exploit a loophole, reported South China Morning Post. The unexpected move will be seen in Tokyo as a "thinly-veiled warning."

An unnamed security analyst with the National Institute of Defence Studies, affiliated with the Defence Ministry in Tokyo, told South China Morning Post that China was showing off its military strength to Japan and its ability to sail where it wants to. Russia too was sending a similar message to the U.S., he said.

He added that Chinese warships' increased access to the Pacific and the east coast of the Japanese archipelago was worrisome as the nation’s most military installations were located in the area. 

James Brown, an associate professor of international relations at the Tokyo campus of Temple University, too considers this "symbolic, but also a real cause for concern." 

"China and Russia continue to get closer together and together they are communicating the message that they can create difficulties for Japan," he was quoted by the outlet. 

However, the Chinese and Russian fleets were closely monitored by Japanese forces, including a Japanese P-3C maritime surveillance aircraft and two minesweepers.

According to the Defense Ministry, the group consisted of five Chinese vessels -- one Renhai class destroyer, one Luyang-III class destroyer, two Jiangkai class frigates, and one Fuchi class replenishment oiler. The Russian fleet included two Udaloy class destroyers, two Steregushchiy class frigates, and one Marshal Nedelin class missile-tracking ship. 

Japan East China Sea Troops Representation. Japanese forces on the East China Sea Photo: Getty Images/AFP/Toru Yamanaka