If you gaze long into an abyss, the abyss will gaze back into you.

We don't want to get into a tit for tat with Iran,

What accounts for TIT fo TAT's roobust success is it's combination of being nice, retaliatory, forgiving and clear. It's niceness prevents it from getting into unnecessary trouble. It's retaliation discourages the other side from persisting whenever defection is tried. It's forgiveness helps retore mutual cooperation. And it's clarity makes it intelligible to th eother player, therby eliciting long-term cooperation. The Evolution of Cooperation, 1984

Whoever is related to me in the height of his aspirations will experience veritable ecstasies of learning; for I come from heights that no bird ever reached in its flight, I know abysses into which no foot ever strayed.

If you stare into the Abyss long enough the Abyss stares back at you.

If anyone offends you do not return tit for tat.