The goals for the Japanese attack were simple. The United States was too much of a threat to their newly acquired territories. With holdings in the Philippines, Guam, American Samoa, and other small islands, Japan was vulnerable to an American naval attack. A swift (quick) first strike against the UNITED STATES PACIFIC FLEET would seriously cripple the American ability to respond to their conquests. As the bombs rained on PEARL HARBOR on the morning of Sunday, December 7, 1941, almost 3,000 Americans were killed. Six battleships were destroyed or rendered unseaworthy, and most of the ground planes were ravaged as well. Americans reacted with surprise and anger.

Most American newspaper headlines had been focusing on European events, so the Japanese attack was unexpected. When President Roosevelt addressed the Congress the next day and asked for a declaration of war, there was only one dissenting vote in either house of Congress. The US declared war on Japan.
Dissenting: having an opinion that goes against the majority

What happened because of the attack in Pearl Harbor?