United States security relations with its allies in Northeast Asia—Japan, South Korea and Taiwan—underwritten by US mutual defense treaties, or Congressional law, are changing. Each alliance, or security partnership, also reveals instances of strong bargaining between the members. However these partnerships also show continuity. Each alliance is now over a half century old and continues in a period of obvious US financial difficulties, and ongoing combat commitments elsewhere. Therefore this paper explores several questions: What are the principal issues, and their background, that are currently challenging each alliance? Could any of these alliances be outmoded now? Or, where utility continues, what adjustments seem appropriate?While exploring numerous issues challenging each of the three alliances or partnerships, this paper gives particular attention to the US Marine/Futenma basing issue in Japan, the ongoing US-ROK “Op Con” transfer in Seoul as the DPRK threat continues, and the Taiwan Relations Act and US arms sales, as they signify American underwriting of a peaceful transition between Taiwan and China. Suggestions for US policies conclude the paper.