As tensions mount over US House Speaker Nancy Pelosi’s potential trip to Taiwan , the Chinese navy has been monitoring the USS Ronald Reagan aircraft carrier’s activities in the South China Sea . The nuclear-powered warship was cruising about 185km (115 miles) from the contested Fiery Cross Reef in the Spratlys chain on Thursday, according to publicly available satellite images. Two other vessels – identified by Vietnam-based maritime observer Duan Dang as a Chinese Type 052D destroyer and a Type 054A frigate – were seen 27km and 23km away. The Reagan and its carrier strike group left Singapore on Monday and headed for the South China Sea, as Pelosi’s trip – which she has not confirmed – causes a ruckus, with Beijing warning that the United States will face “ forceful measures ” if it goes ahead. Beijing sees it as a move that would “seriously violate China’s sovereignty” – it regards Taiwan as part of its territory and has vowed to bring the self-ruled island under its control. The People’s Liberation Army has called on the US to commit to its pledge not to support independence in Taiwan. Pelosi, despite being an American lawmaker and not an official of the executive branch which spearheads foreign policy, has been repeatedly described by Beijing as the “No 3 of the US government”. The US aircraft carrier strike group – which includes the USNS Tippecanoe replenishment oiler and the USS Antietam cruiser – has been travelling northeast and if the vessels continue in that direction they will reach the Taiwan Strait. It comes as the PLA Navy is conducting routine military drills off its southern coast near Guangdong, following exercises in nearby Hainan province. An area in the South China Sea about 89km from Macau will be closed to ships on Saturday for military exercises, according to a notice issued by China’s Maritime Safety Administration. The Gulf of Tonkin off southwestern Guangdong will also be a no-go zone on Tuesday and Wednesday while gunnery exercises are carried out. Song Zhongping, a former PLA instructor, said the US carrier strike group was likely to provide an escort for Pelosi if she proceeds with the trip to Taiwan. “At the same time, before the potential visit, the US will increase surveillance of People’s Liberation Army activities around Taiwan – meaning that the US would deploy a large number of reconnaissance aircraft,” he said. China’s military would also be keeping a close eye on any US aircraft and the carrier strike group. “It’s tit-for-tat and mutual surveillance,” Song said. “The region will be tense for a while.” NBC News reported on Friday that Pelosi planned to lead a congressional delegation to Japan, South Korea, Malaysia and Singapore on Friday, citing unnamed sources. A visit to Taiwan was listed as “tentative” on her itinerary. The South Korean foreign ministry said it could not confirm anything about the trip at the moment. The foreign ministries of Singapore and Malaysia, and Japan’s embassy in Washington did not immediately respond to requests for comment. Song said the PLA could be expected to warn off US aircraft and warships near Taiwan during a possible visit by Pelosi, and that China’s military could also try to make it difficult for the lawmaker to arrive by intercepting her plane as it enters Taiwanese airspace. US President Joe Biden has said that military officials thought it was “not a good idea” for Pelosi to visit Taiwan.