Terrorism is a crime. It's not an act of war, it's a crime.
When terrorism is treated as a crime, something to be dealt with by law enforcement working with security services, results happen. The key is sleuthing, not bombing.
Ask Momin Khawaja, the Canadian foreign affairs department computer tech, who's now facing life behind bars after being convicted, in Ottawa, of five terrorism charges. Evidence adduced at his trial showed that Khawaja was an Islamist extremist who joined forces with likeminded villains in England. He agreed to produce 30-bomb detonators for his chums.
It was police work that brought Khawaja down and a criminal justice system that's put him behind bars for what may well be the remainder of his natural life.
It's not often mentioned, but when it comes to thwarting al-Qaeda, the FBI and the CIA have been vastly more successful than the Pentagon.