Japan did not aggressively attack the mainland United States of America because they were already fighting on two fronts in China and South East Asia. There were however some small attacks of the mainland by the Japanese. In 1942, Japan launched an attack on the Aleutian Islands of Alaska, landing on the islands of Kiska and Attu. They occupied Kiska for almost a year, until mid-1943.
A Japanese submarine also shelled an oil field near Santa Barbara, California and Fort Stevens in Oregon. The Japanese also sent about 9,000 bomb-carrying balloons across the Pacific. Apparently only 1 balloon caused any casualties, five children and their pregnant mother were killed when they discovered the balloon in the woods near their home.