> We've recently seen a truly horrifying terrorist attack, and the response was as brutal as you would expect.

Indeed. And the reason why such an attack happened is because the people who did the attack were the ruling government body of 2 million people for almost 2 decades, and were left to their own devices to build up a large scale attack, involving 1 thousand+ combatants.

And in a few months, those combatants and military infrastructure will be destroyed and not much of a threat.

It turns out that killing your enemies leaves them no longer able to attack you. And leaving them alone and in charge of a psuedo country, lets them built up the capacity to harm you.