BEIJING U.S. National Security Advisor Jake Sullivan arrived in Beijing Tuesday to meet top diplomat Wang Yi for tense talks, as China found itself embroiled in fresh security rows with key American allies Japan and the Philippines. On Monday, U.S. treaty ally Japan scrambled fighters after a Chinese military aircraft's incursion into its airspace, which Tokyo called a "serious violation" of its sovereignty. The Philippine defense chief on Tuesday accused Beijing of being the "biggest disruptor"