They allowed it to happen? You actually believe they had concrete evidence of the date and time of the attacks and did nothing?
It happened to the Lusitania back in 1915. The US government wanted to get into WW1 but the general populace didn't want it. So despite the warnings from the Germans that they'd destroy any vessels in that territory we sent a cruise liner filled with American citizens into that region. We also found out later we were suppling the Brit's with supplies. I wouldn't put it past the government to do it again. I don't trust the government one bit.