The Pentagon's new defence strategy, signed off by United States Defence Secretary James Mattis, confirms a critical shift in thinking that was revealed when Washington published the National Security Strategy at the end of 2017. Where once terrorism was the biggest threat, the new strategies see great power competition - read China, and to a lesser extent, Russia - as the biggest challenge. "Long-term strategic competitions with China and Russia," says the document, "are the principal priorities... and require both increased and sustained investment, because of the magnitude of the threats they pose to US security and prosperity today, and the potential for those threats to increase in the future."

Noting that American victory on the battlefield cannot be taken for granted, the strategists put forth a new security paradigm: build a "more lethal, resilient, and rapidly innovating Joint Force". The need for agility and robust support from allies and partners was also acknowledged. The Nuclear Posture Review subsequently released hints at some of the agile capability sought, in the form of a series of low -yield cruise and ballistic missiles that could be launched from air, land and sea. This is meant to signal to an adversary a greater readiness to use nuclear arms in a conflict. Not surprisingly, that earned accusations from China that the US harbours a Cold War mindset.