TAIPEI, Taiwan — China’s coast guard, the world’s largest maritime law enforcement agency, played an unprecedented role in this week’s military drills around Taiwan, participating in a simulated blockade of the island and raising the chance of escalation as Beijing muddies the waters with “gray zone” tactics.

The drills, which came just days after Taiwanese President Lai Ching-te rebuked Beijing’s claims of sovereignty over Taiwan, included a record-breaking 153 jets buzzing around the island from Monday to Tuesday morning, according to the Defense Ministry in Taipei.

Also for the first time, China’s coast guard fully encircled Taiwan, with the ministry counting 17 of the service’s ships around Taiwan and its outlying islands during the same period. The Chinese coast guard also deployed a new type of huge vessel not previously used in drills around Taiwan and navigated to waters surrounding Taiwan’s Matsu islands where it had not ventured in the past.

While coast guards are widely seen as law enforcement agencies, not as arms of the military, the drills illustrate the Chinese coast guard’s unusually aggressive behavior. They also reveal its increasing role in Beijing’s attempts to assert control over waters like the South China Sea and those around Taiwan.

“The amount of coast guard integration into this exercise is remarkable because it’s something we haven’t seen to this level before,” said Ray Powell, director of SeaLight, a maritime transparency project at Stanford University. “China’s coast guard has become central to China’s strategy of asserting its sovereignty in the places that it wants the other countries to know that it is sovereign.”

Taiwan’s Defense Ministry expressed “strong condemnation” of the drills, which are now common around sensitive political events in the island democracy of 23 million people.

Taiwan is not the only area where China’s coast guard has flexed its power this week. On Thursday, the agency announced it drove away a Japanese fishing boat that “illegally entered” waters near the tiny but disputed Diaoyu/Senkaku islands, which both Beijing and Tokyo claim.

Tokyo, which rejects Beijing’s claim over the islands, did not comment on the incident Thursday.

Chinese coast guard’s unprecedented involvement

After encircling Taiwan and mimicking a blockade that could cut off the island from the outside world, China’s coast guard published a map on social media of its boats around Taiwan in the shape of a heart, likening the surrounding vessels to an illustration of China’s love for its neighbor.

This week also marked the first time Chinese coast guard ships entered the prohibited waters around Matsu, an archipelago of outlying Taiwanese islands, in a military drill, according to a Taiwanese coast guard official speaking on the condition of anonymity to discuss sensitive cross-strait topics.

The Chinese coast guard sent its largest ship, called the 2901, during drills around Taiwan, the official said. The 2901 weighs 10,000 tons and can sail as fast as 25 knots, according to Chinese state media.

The Taiwanese coast guard ships are much smaller and “cannot compare to the big monster,” said Lin Ying-yu, an expert on the Chinese military at Taiwan’s Tamkang University. Why is this concerning?

China’s use of the coast guard around Taiwan fits into a broader category of “gray zone” tactics, meant to menace while stopping short of provoking an outright conflict.

“The coast guard essentially gives China a degree of ambiguity as it uses military coercion against Taiwan in what’s known as the gray zone, below the threshold of the use of force,” said Drew Thompson, an expert on the Chinese military at the S. Rajaratnam School of International Studies in Singapore and a former Pentagon official.

It also muddies the response because China can categorize coast guard activities as law enforcement, rather than military action. In fact, a spokesperson for China’s coast guard described its activities this week as “law enforcement inspections,” according to a statement.

If Taiwan responds to aggression from the Chinese coast guard with its navy, according to Thompson, China has the pretext to bring in its own naval forces while accusing Taiwan of escalating the situation.

“It’s a way of complicating not just Taiwan’s response but the international community’s response,” Thompson said. “By characterizing these vessels as law enforcement vessels rather than navy vessels, it’s essentially claiming that this is a civil, nonmilitary action, and that makes it difficult to respond with military force.”

Other examples of gray-zone tactics China could employ include the use of cyberattacks against Taiwanese critical infrastructure as well as economic punishments like banning certain Taiwanese imports.

Lai, in a speech last month, specifically decried this strategy. “Through its use of gray-zone tactics such as economic coercion and cognitive warfare, China poses serious threats to global peace and stability,” Lai said. “China doesn’t just want to change the status quo in the Taiwan Strait. It intends to change the rules-based international order and achieve international hegemony.”

The rapid expansion of the Chinese coast guard

China’s coast guard has expanded and militarized over the past decade.

It was established in 2013 under the State Oceanic Administration, the government authority previously responsible for regulating China’s coastal areas. Five years later, it was moved under the People’s Armed Police, a paramilitary organization overseen by the most powerful military body in China, the Central Military Commission.

Today, the Chinese coast guard has 150 large vessels — including 20 transferred from China’s navy — some of which are equipped with helicopter facilities, water cannons and guns, according to a 2023 Pentagon report. In addition, it is estimated to have more than 50 medium and 300 small ships.

The coast guard’s legal powers are also growing. In 2021, Beijing passed the Coast Guard Law, which expanded the maritime force’s ability to respond, including with weapons, to foreign ships in areas China deems to be under its jurisdiction. This spring, additional regulations were passed to allow the coast guard to board and detain ships it determines have illegally entered Chinese waters.

If the coast guard boards a Taiwanese ship as the regulations allow, said Bonnie Glaser, an expert on Taiwan at the German Marshall Fund in D.C., “it could result in a confrontation and possibly exchange of fire that would significantly escalate cross-strait tensions.” Chinese coast guard activity beyond Taiwan

The South China Sea and East China Sea have become flash points for clashes between the Chinese coast guard and countries like the Philippines.

In June, the Chinese coast guard forcibly boarded Philippine navy ships in the most serious, recent confrontation in the South China Sea, while the Japanese government complained to Beijing after four Chinese coast guard vessels entered territory that Japan considers its own. In August, coast guard ships from China and the Philippines collided near the Sabina Shoal, a disputed area in the Spratly Islands.

China’s coast guard has also started venturing further afield. It recently entered Arctic waters for the first time in a joint exercise with Russia, according to a post on the Chinese agency’s official social media account early this month.

What is the response to the coast guard’s aggression?

Taiwan is attempting to modernize its own coast guard, but experts say more resources and attention are needed. With a budget of nearly $800 million in 2024 - down 3 percent from 2023 - Taiwan’s coast guard has 164 vessels as of August last year. But many of those ships have been in commission for two or three decades and need upgrades, according to data from Taiwan’s Ocean Affairs Council.

Tamkang University’s Lin said a bigger coast guard budget is necessary, as well as more cooperation with maritime forces from other countries, like the United States and Japan. In 2021, Washington and Taiwan agreed to establish a coast guard working group to improve communication between the countries’ maritime agencies. This summer, Taiwan and Japan held joint coast guard drills off Japan’s eastern coast.

The most important preparation for engagement with the Chinese coast guard, however, may be a mental one.

“It’s important for other countries not to delude themselves that the Chinese coast guard is anything other than a branch of the PLA,” Thompson said, referring to China’s People’s Liberation Army. “The most important thing is recognizing them for what they are.”

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