In what we believe is a significant escalation and potentially a hint as to the president’s thinking, President Trump said during a phone call with Japanese Prime Minister Shinzo Abe that the US remains committed to defending its territories and allies using all “diplomatic, conventional and – here’s the big one – nuclear – capabilities at our disposal.” This is the first time Trump has explicitly referenced possible involvement of nuclear weapons in a US response to its isolated antagonist, and also means that the two world leaders discussed the possibility of a nuclear response.