How were the Japanese able to surprise the US at Pearl Harbor?

The Japanese were able to surprise the US because Japanese aircraft carriers approached Hawaii without being noticed.

Explanation:

The attack on the harbour was a surprise military strike by the Imperial Japanese Navy Air Service against u. s. service base at the harbour, Hawaii Territory, on the morning of December seven, 1941. The attack, additionally referred to as the Battle of the harbour, crystal rectifier to the United States' entry into warfare II. the Japanese military leadership mentioned the attack because of the Hawaii Operation and Operation and as Operation Z throughout its coming up with. The attack commenced at 7:48 a. m.

The Japanese were able to surprise the US because Japanese aircraft carriers approached Hawaii without being noticed