TAIPEI (Reuters) - Taiwan’s air force scrambled on Friday after eight Chinese fighter aircraft flew into the southwestern part of its air defence zone in another display of stepped-up military activity around the democratic island. Beijing, which claims Taiwan as Chinese territory, says it is responding to what it calls “collusion” between Taipei and Washington, Taiwan’s main international backer and weapons supplier. The Taiwanese Defence Ministry said four Chinese J-16s and four JH-7s as well as an electronic warfare aircraft flew near the Taiwan-controlled Pratas Islands in the top part of the South China Sea. The air force scrambled, with “radio warnings issued and air defence missile systems deployed to monitor the activity,” the ministry said. Chinese aircraft fly in the southwestern corner of the zone on an almost daily basis, though the last such large-scale incursion was on Jan. 24 when 12 Chinese fighters were involved. There was no immediate comment from China. Shortly before the ministry’s statement, Taiwan announced a reshuffle of senior security officials including a new, U.S.-trained defence minister, to help bolster military modernisation and intelligence efforts. President Tsai Ing-wen has pledged to defend the island and has made modernising its armed forces a priority, including developing a fleet of new submarines, buying new F-16 fighters from the United States and upgrading its warships. National Security Bureau Director-General Chiu Kuo-cheng, who graduated from the U.S. Army War College in 1999, would replace Yen De-fa as defence minister, Presidential Office spokesman Xavier Chang told reporters. The president expected Chiu to complete the next stage of military reforms, including planning for “asymmetric warfare”, focusing on high-tech, mobile weapons designed to make any Chinese attack as difficult as possible, Chang said. Chiu’s old job as intelligence chief will be taken by Taiwan’s top China policy-maker, Chen Ming-tong, now head of the Mainland Affairs Council. “The most important task of the National Security Bureau is to understand and have a grasp on China,” Chang said. They will take up their posts next week. China announces its 2021 military budget next month at the annual meeting of parliament, a figure closely watched as an indication of its strategic intentions. Last year it set a rate of increase at a three-decade low as the economy wilted during the COVID-19 pandemic. Chinese military expert Ni Lexiong, a retired professor at the Shanghai University of Political Science and Law, said this year it would likely get a big boost, partly due to the increased tensions over Taiwan. “If the mainland wants to liberate Taiwan it needs to make preparations for war, so we need to pump up our equipment,” he said.