A senior former U.S. security official has delivered a striking admission while reflecting on the September 11 attacks, saying those in authority “did not see the nature of the danger in time” to prevent 9/11.The official said authorities did what they knew to do at the time, but acknowledged that “by definition, it was not enough,” while expressing “deep personal remorse” for the trauma suffered by victims’ families and the country. The remarks come 25 years after the attacks, reopening questions over intelligence failures, missed warning signs and America’s response to 9/11.