China test-landed two aircraft on Fiery Cross Reef in the disputed South China Sea on Wednesday in the second mission of its kind in five days. Two civilian airliners were chartered to fly 1,150km from Haikou Meilan International Airport, land on the artificial island in the Spratly chain, and then return to Hainan, state-run Xinhua reported. Another plane took off and landed on Fiery Cross’ new 3km runway on Saturday. Fiery Cross used to be a group of coral reefs underwater at high tide until a massive works programme turned it into a 2.8 square kilometre island. Its airport can handle a Boeing 737 as well as medium-sized Chinese air force jets. It is one of seven sites in the Spratly Islands on which China is reclaiming land and building civil and military facilities. Vietnam, which also claims sovereignty over the reef, protested against the Chinese test flights on Saturday. READ MORE Beijing rejects Vietnam protest over South China Sea landing Beijing responded by saying such activities were “completely within Chinese sovereignty”. “The Chinese government is chartering civilian aircraft to test the airport is see if the facilities meet civil aviation standards,” foreign ministry spokeswoman Hua Chunying said at that time. The Philippines, Indonesia, Malaysia, Brunei and Taiwan also have competing claims in the South China Sea, a region covered by some of the world’s busiest air routes. China’s ambitious construction programme has ignited concern and protests from its Southeast Asian neighbours. The United States also sent guided-missile destroyer USS Lassen and a B-52 bomber to patrol near 12 nautical miles of China’s artificial islands over the past two months. READ MORE: It’s official: China building second aircraft carrier as concern mounts over claims to South China Sea Analysts said China was using the tests to signal its determination to continue development of the islands. “The message is clear. China will carry on with its plan in the South China Sea islands no matter how much opposition there is,” said Hu Bo, a researcher at Peking University’s Institute of Ocean Research. Sending civil aircraft rather than fighter jets was a sign of restraint, he said. But the facilities on the island would indeed be of non-military use in the future. Xinhua said the test proved the Fiery Cross airport was fully operational for civil aviation and would be an alternative location for international airliners flying over the region.