China has lodged stern condemnation to the U.S., as President Joe Biden's latest comments on Taiwan violate Washington's policy toward the island. In an interview with CBS, Biden said his troops would defend Taiwan against "an unprecedented attack." White House Indo-Pacific coordinator Kurt Campbell said Biden's remarks "speak for themselves," and that U.S. policy had not changed. CGTN spoke to Rong Ying, Vice President of the China Institute of International Studies, he says playing the Taiwan card harms U.S. own credibility.