Beijing concluded 2017 with a series of high-profile exercises by the People’s Liberation Army Air Force (PLAAF) circumnavigating Taiwan. Both developments have direct implications for Taiwan’s defense posture. ROCAF training areas are sandwiched between two civilian corridors: M503 and long-established routes along Taiwan’s western coastline. The Taiwanese air force previously vacated one of its training zones after Beijing announced its East China Sea Air Defense Identification Zone (ADIZ) in 2013. Michal Thim is a Taiwan defense specialist, a Research Fellow at the Prague-based think-tank Association for International Affairs, a member of CIMSEC, an Asia-Pacific Desk Contributing Analyst for Wikistrat, and a founder of Taiwan in Perspective.