The U.S. cut off the supply of oil to Japan, which forced them to take some action against the US.
There are many records of communications by both the US Navy and Japanese Navy which make it clear the US knew the attack was coming, and purposefully did not tell the military leaders in Hawaii. Churchill wrote in his Nobel Prize winning series on WWII that FDR knew about the Japanese plans to attack Pearl Harbor.
That is 2400 American deaths, purposefully allowed by the president of this country.
In addition, 8 ships were sunk, and 188 planes destroyed, with a further 162 planes damaged
This one case, which is of the same scope as the Sept 11th attacks on the World trade Center, shows that the US government is capable of conceiving, implementing, and carrying out the attacks on the World Trade Center, massive attacks on its own citizens.
[ Churchill on FDR | Background Info ]