The Pentagon is urgently reviewing just how and when the president might launch nuclear missiles as a dangerous new nuclear arms race breaks out.

Hypersonic missiles are capable of flying at around 12,000 miles per hour, or Mach 20. That would reduce the US response time to as little as five minutes — too short for the president to enter the launch codes into the ‘football’ (actually a briefcase) that is never more than a few feet away.