China described its military exercises near the island of Taiwan as “combat drills” Wednesday. The military activity takes place as former U.S. officials arrive in Taipei to signal President Joe Biden’s support for Taiwan’s democracy. Taiwan has said that Chinese fighter jets and bombers have entered its air defense zone. A Chinese aircraft carrier has also been performing exercises near the island. Twenty-five Chinese air force planes, including fighters and bombers, entered Taiwan’s air defense zone on Monday. It is the largest entry into areas controlled by Taiwan reported in recent years. Chinese spokesman Ma Xiaoguang said the military activity was necessary to answer Taiwan’s independence efforts and “Taiwan-U.S. collusion.” He said that Taiwan’s government is working with “external forces.” In the past, China has given little explanation for its military movements near Taiwan. Its defense ministry only called them “military activities” in January. China considers Taiwan a rebel territory although the two sides have had separate governments since 1949. The United States has not formally recognized Taiwan’s government since 1979. However, the U.S. remains the island democracy’s strongest ally. U.S. officials have been watching the growing tensions with China with concern.