In a new arms deal with Seoul, the Biden administration has agreed to periodically deploy US nuclear-armed submarines to South Korea and involve Seoul in its nuclear planning operations. In return, South Korea has agreed not to develop its own nuclear weapons. The backdrop to all of this is the rising concern about the nuclear threat posed by North Korea. Marco Werman explores the details and meaning of this new arms deal with David Kang, a professor of international relations at the University of Southern California and director of its Korean Studies Institute.