• PLA destroyers Lhasa and Chengdu sailed through near the Chiba prefecture Monday
  • Chinese media said the transit was a warning to Japan over the Taiwan issue
  • Japan had protested China's plans to set up a gas drilling facility in the East China Sea

Japan continues to be on high alert after spotting an increased activity by Chinese and Russian warships near its coast. A day after 16 Russian naval vessels sailed around Japanese islands, three Chinese destroyers were seen sailing near the Chiba prefecture Monday.

Japan’s defense ministry said two Chinese guided-missile destroyers and a supply ship sailed through an area to the southeast of Chiba prefecture, South China Morning Post reported.

The flotilla, led by Type 055 large destroyer Lhasa, reportedly sailed from northwest to the east and south sides of Japan on Monday and Tuesday after making transits in three strategic straits near the island country. The ships appeared to be circumnavigating the Japanese archipelago but were outside the territorial waters, the report added.

Lhasa was accompanied by Type 052D destroyer Chengdu and the Type 903A replenishment ship Dongpinghu.

A PLA Navy flotilla reportedly entered the Sea of Japan on June 12 for drills. They exited the region and entered the Pacific Ocean between Thursday and Friday. While Lhasa and Chengdu sailed via the Soya Strait, Dongpinghu and spy ship Tianlangxing sailed via the Tsugaru Strait in the north of Japan.

The Japanese claim of warships circumnavigating the archipelago was acknowledged by Global Times, the Chinese state-backed media, too. The report, quoting analysts, said the transit by PLA vessels was a warning to Japan against its "repeated provocations over Taiwan question." It is also significant that the vessels sailed through the east side of Japan where the most important Japanese and US military bases are located.

The relations between the two countries worsened after Tokyo began openly expressing its support for Taiwan, which Beijing claims as part of its territory. Recently, Japan protested against what it called China's unilateral exploration of resources in the disputed waters of the East China Sea.

The Chinese actions come after Tokyo claimed it tracked at least 16 Russian naval vessels sailing around the country's home islands and other outlying areas it controls.

According to the Japanese Self Defense Force, five Russian vessels were spotted sailing into the East China Sea from the Philippine Sea via the waters between the Japanese islands of Okinawa and Miyakojima. The fleet included the destroyer Admiral Panteleyev, missile range instrumentation ship Marshal Krylov, and corvettes Sovershennyy, Gromkiy and the Hero of the Russian Federation Aldar Tsydenzhapov.

More warships were spotted in the next few days, and according to the Russian Defense Ministry, the ships were on their way to the East China Sea to take part in exercises that included on-air defense, anti-submarine warfare and search and rescue operations.

The East China Sea
Vessels from the China Maritime Surveillance and the Japan Coast Guard are seen near disputed islands, called Senkaku in Japan and Diaoyu in China, in the East China Sea, in this photo taken by Kyodo on Sept. 10, 2013. Reuters