At least McGrath has had some experience with terrorist threats but even his enemies pale in comparison with the Islamic fundimentalists.
The Germans who attacked England in the early 1940s were identifiable and had a country that could be attacked in retaliation.(There were, in fact, retaliatory responses by the RAF and, later, by the land and air forces of the Allies.) Al Qeda has no "official" state to accept responsability and to answer for there offenses.
The IRA was, and is, a paramilitary orginization that, for the most part, employed military targets and customarily prewarned civilian targets. Whatever one's position on the Irish question, no one can suggest that the IRA attacks were not specific or that their goals were not reachable through negotiation and compromise. Al Qeda's goals are religious and not subject to compromise. Their targets are general and designed to kill as many people as they can.
Those nations that have been dealing with these nuts for decades know, only too well, that they are insatiable and without pity or empathy. Israel, Lebanon, Syria, Iran, Afghanistan, Egypt, Jordan and Saudi Arabia have lived with the threat of Islamic fundimentalism for forty years. Some have appeased them in hopes they would just go away.
(They don't go away. They never go away.) The USA is now facing their threats. How we respond will determine our resolve and courage.