Pearl Harbor, of course, was the US naval base subjected to a surprise air attack by Japan in December 1941 during the Second World War. Confirming that the US treasury had bought billions of dollars’ worth of Japanese yen, Trump said: “Japan’s been very good to us, with the exception, of course, of Pearl Harbor... they were not good.” It's not the first time Trump has spoken about Pearl Harbour during his time in office. The president faced a fresh wave of condemnation after he decided to joke about Pearl Harbor in front of Japanese prime minister Sanae Takaichi back in March. Why didn’t you tell me about Pearl Harbour?”