Why was Japan so successful in their attack on the US?
At Pearl Harbor it was that they had achieved total surprise and
benefited by some mistakes made by the U.S. military.
In the Philippines it was because of the low priority given to
building up that country until it was too late AND some major
mistakes by Douglas MacArthur and his staff.
Attack on Pearl Harbour wasn't such a big success as it seems. The
most importand targets like carriers, docks, fuel supplies
Japan was successful because the US saw them on the radar but
thought they were the B-12 bombers scheduled to land. The US took
no notice but monitored them. By the time they came in so fast that
the lookouts didn't have enough time to tell everyone they were
under attack. Finally, the attack was successful because they
caught Pearl Harbor asleep by attacking them on a Sunday morning.