Chinese leader Xi Jinping met with US National Security Adviser Jake Sullivan on Thursday at the end of the latter's three day trip to Beijing, which is a first such trip for a sitting US national security adviser in eight years.

But the most interesting and tense moment came just before that, when Sullivan met one of China's vice chairs of the Central Military Commission, Gen. Zhang Youxia. The top general confronted Sullivan on growing US support for Taiwan's military. Zhang informed Sullivan that reunification of Taiwan with the mainland is "the mission and responsibility" of the Chinese PLA military and that it won't be deterred. Sullivan looked nervous and unsettled throughout the whole encounter, with Zhang confident and beaming.