Geography has given the US unrivaled security. Trump is destroying it

The secret to American power and pre-eminence was best summed up more than a century ago. America, observed Jean Jules Jusserand, France's ambassador to the United States during the first world war, "is blessed among the nations". To the north and south were friendly and militarily weak neighbors; "on the east, fish, and the west, fish". The United States was and is both a continental power and, in strategic terms, an island - with all the security those gifts of geography provide. No world power has ever been as fortunate. This unique physical security is the real American exceptionalism. Americans…