October was the busiest month by far, with Taiwan’s Defense Ministry reporting 196 sorties by People’s Liberation Army aircraft flying into its air defense identification zone. An ADIZ extends beyond a nation’s territorial airspace and is used for logging approaching civilian and military aircraft, but it is not regulated under international law.

The PLA’s frequent training missions are mostly concentrated within a band of international airspace about 100 to 150 miles southwest of the island, but the message they send is clear.

The White House, State Department and Pentagon have backed Taipei against what the Biden administration describes as intimidation by Beijing.

China says its military flights target “Taiwan independence” and “external forces”—the latter being a familiar reference to the United States.

The majority of October’s nearly 200 Chinese military flights near Taiwan occurred in the first four days of the month, when the PLA flew a combined 149 sorties as part of large-scale training exercises that coincided with its 72nd National Day celebrations. September was the previous highest month with 117 sorties.

According to official government data compiled by Washington-based defense analyst Gerald Brown, there have been 895 sorties into the ADIZ since Taiwan’s Defense Ministry began reporting the activity last September. As of Tuesday, this year’s total stood at 725, with China likely to double its 2020 total of 380 flights before the end of the year.

Brown told Newsweek that last month’s sorties included a drastic increase in attack aircraft such as the J-16 striker fighter, particularly between October 1 and 4. Last week, the PLA also few two helicopters into Taiwan’s ADIZ.

There was a pattern involving more J-16s whenever China was “making big shows of force,” he added.

The escalation of tensions across the Taiwan Strait has left officials in Taipei and Washington deliberating over whether a decades-long balance of deterrence is slowly slipping away under the PLA’s growing capabilities.

But beyond the obvious political signaling that comes with sending fleets of fighter aircraft near Taiwan, observers have also noted the Chinese military’s more practical aims for routinizing their training in the Bashi Channel south of the island. The waterway links the Pacific to the Taiwan Strait and the South China Sea, and the deep-sea corridor also provides relatively safe passage for submarines.

Analysts say it is one of the areas where the PLA expects to blockade Taiwan and deprive it of outside assistance from the U.S. and its allies. Meanwhile, regular U.S. Air Force and U.S. Navy deployments into the same space speak to active attempts to counter China’s anti-access and area denial (A2/AD) strategy.

On Sunday, as Taiwan detected a PLA Y-8 anti-submarine warfare variant traversing the Bashi Channel to patrol the island’s southwestern coastline, Japan reported three Chinese support aircraft flying from the East China Sea into the Pacific via the Miyako Strait, between the Japanese islands of Miyako and Okinawa, where the bulk of forward-deployed American troops are stationed.

The exercise, which had PLA aircraft on Taiwan’s flanks, was repeated on Monday with a similar composition of Chinese planes.

When a similar pincer-like movement occurred in March, Taipei-based analyst Su Tzu-yun told Newsweek the maneuver was the PLA’s “showing it has the capability to isolate Taiwan if the U.S. and Japan plan to assist.”

China’s air and sea superiority over the Bashi Channel and Miyako Strait will be vital for the PLA in wartime, said Su, who is a fellow at the Institute for National Defense and Security Research in Taiwan. They are some of the few international waterways Chinese naval forces can use to reach the Pacific. Both are also major chokepoints in the island chain strategy.