Taiwan released a defense report on Tuesday that for the first time cites concerns about heightened Chinese military activities in the western Pacific and Japanese waters.

"Our biggest security challenge comes from the military threat of the Communist Party of China," the 2017 National Defense Report says.

While the Chinese People's Liberation Army began its long-distance training in the western Pacific before President Tsai Ing-wen took office in May 2016, the 14th biennial report points out that the number of Chinese warplanes as well as their frequency and varieties have increased since August last year.

As of last month, China has sent warplanes to the western Pacific 26 times, and China's first aircraft carrier, the Liaoning, and its accompanying ships have passed through the Taiwan Strait four times, according to the report.

"The reconnaissance area of the Chinese military has covered the entire western side of the second island chain," it said, referring to a strategic line of defense east of the "first island chain" linking Japan's Ogasawara Islands and the Mariana Islands.

The so-called "first island chain" is a sea defense line formed by the Aleutians, the Kuriles, the Japanese archipelago, the Ryukyu Islands, Taiwan, the Philippines and Borneo.

Japan also feels the pinch. It scrambled fighter jets 1,168 times to head off aircraft approaching its airspace in fiscal 2016 ended March 31 this year, with the number exceeding the previous record set during the Cold War, according to the Japanese Defense Ministry.

In addition to the reconnaissance capability, the PLA Air Force has achieved air supremacy in areas west of the "first island chain" with its multi-layered firepower, united air defense system and anti-missile capability, the Taiwanese report says.

Situated at a strategically important position of the "first island chain," Taiwan faces a tremendous threat from short- and medium-range ballistic and cruise missiles that China has deployed, which can launch precision strikes against it.

China has also strengthened its development and deployment of long-range anti-ship ballistic missiles, making it more difficult for international intervention should a war break out in the Taiwan Strait, a 160-kilometer-wide body of water separating Taiwan and mainland China.

As for China's overall naval combat capability, the report says the PLA Navy possesses the capability of launching a nuclear counter-strike as well as countering foreign intervention and implementing a naval blockade in the strait.

The PLA ground force is making great efforts to achieve the short-term goal set by Chinese President Xi Jinping, which is to gain substantial improvement in "mechanization, informatization and strategic capability" by 2020.

Xi also set a midterm goal for the Chinese military: to turn itself into a modernized force by 2035. The long-term goal is to become a world-class military by 2050.

As for the cyber warfare, the report says advancements in the PLA's capabilities present a significant challenge to Taiwan.