So the author is at a loss for the real solution, because he didn't come up with any in the entire article. Except for not retaliating, which I don't think is a solution.
I was born in a country that (somewhat) supported terrorism - Czechoslovakia. Eventually we switched sides (and later also somewhat supported terrorism again). Why did we switch sides? Because our emigrants received support from the West (while we were receiving very little terrorism). The West didn't engage the Warsaw pact directly (or semi-directly through terrorism), but through cultural war. That's why (at least I think) the West was successful in the Eastern Europe, but not in the Latin America, or in the Middle East.
In my opinion, immigrants are the key to successful foreign policy. The reason they are coming is because you're doing something better than their home leaders. And they will tell their relatives in their home country that, very passionately.
The terrorism is short-term strategy of states or other groups that are massively losing the cultural war (kinda like firing employees to boost profits). The long-term strategy is outlined above (and as every long-term strategy it entails element of getting better). So don't worry about the culture; if your opponent resorts to terrorism, your culture has already won!
Unfortunately, multiculturalism has often been used as an excuse for not doing enough. Many times I have heard police to say (about some atrocity that happened in some subculture) that this is "how they do things in their culture/community". It's unacceptable excuse for not doing the job.
Appeal of radicalism is ultimately a social issue like many others (say, appeal of drugs, appeal of violence), and it should be dealt with as such. People on the right don't like the idea of telling somebody what to do at someone else's expense, but I am afraid that good prevention (access to education, having good job) is the only thing that really works here.
Whether citizens will accept the above is of course up to them, but I am convinced (from empirical evidence) that this is the best way to handle the problem in open society. If, on the other hand, the goal is to remove as much terrorism as possible, then the open society is perhaps no good. If you close off borders, have isolationist foreign policy, and establish a semi-totalitarian regime, you will probably get less terrorism (this was case of Czechoslovakia in the past). But this strategy probably comes with its own set of disadvantages (according to this list https://en.wikipedia.org/wiki/List_of_countries_by_immigrant..., the only country that seems to be worth immigrating into with low amount of immigrants is Japan).
How do you retaliate against a concept? The US has created more terrorists in the last 14 years by attempting to do just that.
Mental game: you're a terrorist. For the sake of the exercise your enemy is daytime television. Teletubbies bomb your house from the sky and in the process your wife and daughters, all innocent, are killed. The only survivor - your son. Your son now hates Teletubbies. He fucking hates them. Consider that he might want to exact revenge. Daytime television now has a new enemy, assuming he has no friends or other family members sympathetic to his plight. If he does, you have more than one new enemy.
As others have said, bombing didn't work the first time...
His post also seems to suggest that ISIS derives their control over the people in their territory through popular support. This is not the case. Most of the populace is simply trying to survive ISIS rule, as is typically the case in totalitarian regimes. Sadly, the reality of the situation in Syria and Iraq is that there aren't really alternatives the people find worthy of risking their necks to rally behind. And the brutality of the official regimes and those regimes' allies, combined with the brutality of ISIS, preclude better alternatives from presenting themselves.
And none of this can be divorced from the geopolitical situation. The calculus of nuclear non-proliferation, our eternal chess matches with Russia and China, and energy politics have shaped our strategy from the start, and largely led to the outcomes we've seen. If not for these things, we may have supported a partitioning of Iraq early on, knowing that the Arab Shia portion would have naturally aligned itself with Iran, an independent Kurdistan would have deeply upset our Turkish allies, a new Arab Sunni land would have been a big question mark, and the cities and resources would have been very difficult to allocate.
But now, such a partition seems like it wouldn't have been the worst idea in the world, and has largely de facto happened under very poorly controlled circumstances.
way to go.