Taiwan scrambled interceptors on Sunday morning and broadcast warnings after two PLA J-11 fighter jets crossed the median line and entered the island’s southwestern airspace.

Despite those warnings, the Chinese fighter jets continued their incursion for about 10 minutes – unusual compared to earlier intrusions, in which Chinese aircraft would quickly return to the China side of the median, Taiwan’s military officials said, adding that the planes were about 185 kilometres (114 miles) from Taiwan proper.

Taiwan’s Foreign Minister Joseph Wu told reporters at the legislature on Monday that the line crossing was an intentional act, calling it provocative and dangerous. He said Taiwan had informed “regional partners” about the incident.

Analysts in Taiwan said, while it remained to be seen how Beijing would react to the order to forcefully disperse any future incursion by PLA jets, Tsai could risk setting off a cross-strait conflict which might drag Washington into the situation.

“There is such a risk, but I believe [Taiwan’s] military has its standard operating procedure in dealing with Chinese warplanes straying into Taiwan’s airspace,” said Chieh Chung, senior research fellow of the national security division at the National Policy Foundation in Taipei.

Chieh said Tsai should know her response risked sparking a new cross-strait row, but that she had to act indignantly and boldly while seeking re-election next year.

“After all, mainland China was the one to blame for breaking the tacit agreement by making the incursion,” he said.

Tsai, who Beijing has refused to talk with since her refusal to accept the one-China principle in 2016, has sought to bolster Taiwan’s air power with the purchase of latest-model F-16V fighters from the US.

The US representative office in Taipei, the American Institute in Taiwan (AIT), on Monday said the incursion was an effort by Beijing to alter the status quo, and it would be harmful to regional stability.

“Rather, they undermine the framework that has enabled peace, stability, and development for decades,” AIT spokesperson Amanda Mansour said, while reiterating Washington’s position that Beijing should stop its coercive efforts and resume dialogue with Taipei.

The Defence Ministry in Beijing did not respond to request for comments on Monday.

Analysts in Taiwan said the incursion was intentional and a response to US naval “freedom of navigation” exercises in the strait.

It also demonstrated that Beijing had discounted Taiwan’s reaction over the intrusion and that China felt any provocative action by the US in the Taiwan Strait and US deployments in Indo-Pacific region must be stopped, they said.

“Judging from the fact that the PLA warplanes have also intruded into the air defence identification zones of both Japan and South Korea [in the past year], Sunday’s incursion was more [about] countering the US’ deployments in the Indo-Pacific region,” said Doong Sy-chi, director of international relations at Taiwan Thinktank, on Monday.

“It also means that the communist leadership no longer care about the reaction of Taiwan as they used to do out of the concerns that it [incursions] would increase Taiwanese resentment against Beijing and boost the pro-independence camp’s chances in [Taiwan’s] 2020 presidential election,” he said.

Wu Chien-chung, professor of general education at Taipei University of Marine Technology, noted that since January, the US had sent warships to cross the Taiwan Strait each month in a gesture that all foreign vessels can travel what is an international waterway.

“We can keep watch of whether the US will continue to send warships to cross the Taiwan Strait on April 24 as it has done on January 24, February 24 and March 24, and to see the reaction of the mainland if it happens again on April 24,” Wu said.

Fan Shih-ping, political science professor of National Normal University in Taipei, said he was concerned whether the decision to proceed with the flight was taken by PLA theatre command or was an explicit order from Chinese President Xi Jinping.

“Intrusions like this could become bigger and more frequent as long as the US continues its Indo-Pacific security policy, and eventually there could be intrusions into our Penghu’s [islands] airspace, which is closer to Taiwan than Sunday’s intrusion location,” Fan said.

“What I am worried about is that the US would follow up with bigger and stronger action,” he said, adding that Washington could be forced to offer greater support for Tsai and her pro-independence Democratic Progressive Party.

Chieh said Beijing’s intention was to warn both the US and Taiwan, whose political and military cooperation have become stronger every day.

Hong Kong-based military commentator Song Zhongping, said such incursions would “no doubt” become more frequent in future in response to the regular US warship patrols in the strait and closer US-Taiwan military cooperation.

“Beijing’s move was a ‘reciprocal escalation’ of the crisis, since the situation has escalated,” he said.

Song pointed out that the median line was a legacy dating back to 1955 and the latest move showed the PLA was determined and capable of breaking this “outdated” rule.

“The PLA’s goal is reunification and for them this line has to be broken anyway, sooner or later,” Song said.

“But for now both sides are likely to also show restraint and avoid any direct skirmish.”

About 160 kilometres (100 miles) wide at its narrowest, the Taiwan Strait opens at its southern end into the South China Sea, where Taiwan and the Chinese mainland share overlapping territorial claims. Since the two sides split amid civil war in 1949, China has claimed Taiwan as its own territory, to be absorbed by force if necessary.

additional reporting by Liu Zhen