WATCH: Donald Trump cracks Pearl Harbor joke when pressed on lack of Japan warning over Iran

US President Donald Trump has cracked a Pearl Harbor joke when grilled by a Japanese reporter on the nation's lack of warning amid the Iran war.Addressing a press conference with Japanese Prime Minister Sanae Takaichi, Mr Trump told the reporter: "One thing you don't want to signal too much, when we go in, we went in very hard, and we didn't tell anybody about it because we wanted surprise. "Who knows better about surprise than Japan? Why didn't you tell me about Pearl Harbor?"WATCH ABOVE.