US President Donald Trump compared his administration's surprise military actions against Iran to Japan's 1941 attack on Pearl Harbor during a meeting with visiting Japanese Prime Minister Sanae Takaichi on Thursday.

The remark came amid a tense exchange in which Trump defended his decision not to notify US allies in advance of the operations against Iran.

"I didn't inform our allies because I wanted it to be a surprise," Trump said, adding, "Who knows better about surprise than Japan? Okay, why didn't you tell me about Pearl Harbor?"

On the morning of December 7, 1941, Japan launched a surprise attack on the US naval base at Pearl Harbor in Hawaii, resulting in nearly 3,600 American casualties. Then-President Franklin D. Roosevelt called the day "a day of infamy," and the attack prompted the United States to formally enter World War II.