The Chinese Foreign Ministry summoned U.S. Ambassador Nicholas Burns after US Speaker Nancy Pelosi landed in the Taiwan region. Chinese Vice Foreign Minister Xie Feng called Pelosi's trip a wilful act to violate China's redline and the China-U.S. Joint Communique, the political foundation of bilateral ties. He noted that the U.S. administration indulged rather than restrained Pelosi's trip. China has responded with multiple statements and live-fire drills around the island. What's the impact of Pelosi's sneaky visit to Taiwan on cross-strait relations? What's the rationale behind China's reaction before and after she landed?