That article will likely be dismissed by many Americans as left-wing moralizing, even by those who remember that the British public was overwhelmingly against the invasion of Iraq. But if you pay a little more attention, it's actually a pragmatic recognition of several issues that Americans do not want to deal with.
The first is that terrorism, or more correctly violence, does work. Indeed, for minorities or other effectively powerless people, it is almost always the only practical option. No-one in Britain is under any illusion that their parliament suddenly started to care about the catholics of Northern Ireland: they know that bombs made their politicians sit down with the IRA. Here in the US, you could try to argue that Martin Luther King made peaceful progress, but how much progress would have been made without the revulsion to the violence turned against colored Americans because of the activities of his and other civil rights movements.
The other piece of political rhetoric most people in Britain do not buy into, is the promise that terrorists will be punished. Certainly some will die and some will be imprisoned, but those who stay the course will be pardoned and handed back normal lives. Some will even be feted. Brits know this from their experience with both the IRA and 50 years earlier, with Israel. Come to that, if Americans were better informed, they would recognize how easily their own government is willing to forgive or at least forget. Check out:
http://www.mideastweb.org/lavon.htm (btw earlier this year it went almost unnoticed in the media here that the Israeli president honored the 3 surviving members of the Lavon Affair) and
http://www.ussliberty.org/
Politicians initially address their electorates with stirring words, knowing at this point that most people want reassurance and the promise of revenge. But there isn't an experienced politician on the planet who doesn't know full well that ultimately both national pride and moral arguments are completely irrelevant. if violent opponents show sufficient resolve, striking often enough and with sufficient impact to energize a normally complacent public, they will eventually win. Summed up, the Guardian article does no more than imply an awareness of that reality and state more bluntly the other obvious truth: namely that in the real world, actions do cause reactions.