Is China winning the nuclear arms race?

China might just have taken a big step forward in its nuclear capability. It's reportedly been testing space missiles which could get around US defences, meaning that, theoretically, it's able to launch a nuclear strike on US soil. So how is the US likely to respond? Today on The Signal, China's expanding nuclear ambitions. How does a race like this end? Featured: Dr Jeffrey Lewis, Professor, Middlebury Institute of International Studies in California & Director, East Asia Nonproliferation Project