The number of entries by Chinese military aircraft into Taiwan's air defense identification zone has topped 140 in just four days.
Taiwan's defense ministry says 56 Chinese fighters, bombers and other aircraft entered the zone, which is over waters southwest of Taiwan, on Monday.
The figure marked the highest number of Chinese aircraft tracked in the zone in a single day since the ministry began releasing such numbers in September of last year.
The number of such incidents has spiked since October 1, when China observes its national foundation day. The cumulative figure for the first four days of October has reached 149.
During the first two days of October and on Monday, many of China's mainstay fighters flew into the zone not just during the daytime, but also during night.
Chieh Chung at Taiwan's National Policy Foundation says these moves suggest China has more mainstay fighters in its fleet and has improved its capability of multi-unit operations and pilots' ability to fly at night.
Taiwan's Mainland Affairs Council issued a statement demanding that China immediately stop what the council called non-peaceful and "irresponsible provocations".
The council added that the actions significantly hurt peace and stability across the Taiwan Strait and heighten regional tensions.
On Monday, China reacted to a statement from US State Department spokesperson Ned Price urging Beijing to stop its military pressure on Taiwan.
Chinese Foreign Ministry spokesperson Hua Chunying said, "Taiwan belongs to China and the US is in no position to make irresponsible remarks."
Hua said the US has been making "negative moves," including planned arms sales to Taiwan and frequent sailing of US warships through the Taiwan Strait.
Hua said, "these provocative moves undermine China-US relations and regional peace and stability. China is firmly opposed to them and has taken necessary countermeasures."