He was addressing individuals, not nations.

I cannot forgive one who offends you. If I have taken on the task of defending someone, and a third person attacks me, I can turn the other cheek, but if the third person attacks someone who I have promised to defend, and threatens to do so again, turning the other cheek is an offense against someone who trusted me.

By refraining from massive and indiscriminate retaliation, we show ourselves as sane.

I have no desire for retailiation. Not even a hope for justice. There will be no justice, because those who did this have nothing to offer, nothing to lose, that comes close to compensation.

What I want is for them to be stopped. Or reduced in effectiveness.

If providing them a lifetime supply of hash and hookers would stop them and not encourage others, I would not object to that solution. Unfortunately, I don't see any viable solutions that do not involve some level of military force.