Re: Star Trek III - The [Speculation Begins] (Spoilers)
With the year long gap between the incursion on Kronos and the epilogue of the film leading into the Enterprise's five year mission, it seems as though either relations with the Klingons have improved or remained stagnant, or they're just really slow to respond.
The After Darkness
comics take a different approach because they apparently lack the one year time jump, but in the movie, I would think that if the Klingons were going to retaliate in force, they would have done so by now. Maybe the destruction of Praxis and the poisoning of their atmosphere is too much of a distraction for them to be able to afford a costly war with the Federation, so they've just been posturing instead.
My name is Ozymandias, king of kings: Look on my works, ye Mighty, and despair!
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.