TAIPEI--Taiwan’s military has launched aircraft to intercept Chinese planes more than twice as much as all of last year, the island’s defense ministry said, describing Taiwan as facing severe security challenges from its huge neighbor.

China, which claims democratic Taiwan as its own territory, has stepped up its military activities near the island, responding to what Beijing calls “collusion” between Taipei and Washington.

In the past few weeks, Chinese fighter jets have crossed the mid-line of the Taiwan Strait, which normally serves as an official buffer between the island and the mainland and have flown into Taiwan’s southwestern air defense identification zone.

In a report to parliament, a copy of which was reviewed by Reuters, Taiwan’s Defense Ministry said so far this year the air force had scrambled 4,132 times, up 129 percent compared to all of last year, according to Reuters calculations.

China “is trying to use unilateral military actions to change the security status quo in the Taiwan Strait, and at the same time is testing our response, increasing pressure on our air defenses and shrinking our space for activity,” it said.

The rapid development of China’s military has been accompanied by “targeted” military actions against Taiwan, the ministry added.

China has been particularly angered by growing U.S. support for Taiwan, including senior U.S. officials visiting the island, adding to broader Sino-U.S. tensions.

While Taiwan is unable to compete numerically with China’s armed forces, President Tsai Ing-wen has been overseeing a military modernization program, aiming to make the island’s armed forces more nimble and Taiwan more difficult to attack.

Addressing a Taiwan-U.S. defense conference late Monday, Vice Defense Minister Chang Guan-chung said China has been ramping up what he called “realistic training against Taiwan”.

“We are developing systems that are small, numerous, smart, stealthy, fast, mobile, low-cost, survivable, effective, easy to develop, maintain and preserve, and difficult to detect and counter,” he said.

Chang called for enhanced cooperation with the United States that goes beyond weapons sales, saying that would further invigorate Taiwan’s defense reform and military modernization.

“We will also emphasize joint effort in training, operational concepts, capability assessment, intelligence sharing, and armament cooperation. These are equally important as the acquisition of hardware,” he said.