The West, understandably, doesn't want to punish people for crimes not committed. There is great discomfort at implementing a "future crime" scenario as in the movie "Minority Report."
However, most people would agree that for people who could pose a future threat, who have stated an intent to kill Westerners, it is prudent to keep a close eye on them and to be ready if and when such a threat materializes.
And, aside from the loony tree-hugging Left, most reasonable people would agree that Western powers are quite justified in responding forcefully and directly to successful terror attacks.
But when dealing both with terror and crime, for some reason the West is lenient on those whose attacks are not successful. Only when there are mass casualties is there any resolve to strike back, hard, at the terrorists. When the damage is "limited"or the plot is foiled, then it is only expected to give a "proportional" response. For some reason it is not considered fair to have a massive counterattack when the terrorists didn't fully succeed.
This makes no sense. Sending a few cruise missiles, as Clinton did after the 1998 Al Qaeda attacks on US embassies (when "only" 200 people died), is not only ineffective - it is counterproductive. It emboldens the terrorists to try again.
Today was not the first time that terrorists targeted London. Scotland Yard has foiled other attacks. It seems obvious to me that when a country or an organization intends to kill massive numbers of people, and shows its seriousness by actually attempting such an attack, that one is morally obligated to pro-actively make sure that this nation or organization is not going to remain a threat.
Right now, in almost all cases, Islamic terror pays. Terror is being rewarded today in Israel and elsewhere and it has been successful in making heroes out of Muslim murderers throughout the world. Terrorists get fame, they get recruits, they get money, and they get political results. Unless this calculus changes dramatically, unless there is a concerted and united effort to make sure that terrorists will lose far more by each attack than they gain, we will continue to see more and more days like today.