Heck, they went and wiped out the Tribble homeworld. The harmless Tribbles!
There are no words in the Klingon language to describe just how much they HATE tribbles. That one campaign alone probably required decades of systematic asteroid bombardment, not to mention the warriors needed to hunt the little bastards across the galaxy to the last one.
While the Great Tribble Hunt is indeed worthy of song, it's more the Hunt than the destroying the Tribble homeworld. According to the TNG technical manual, a single photon torpedo can carry 1.5 kg of antimatter. Just a regular explosion with that would be almost 65 MT - Tsar Bomba was only 50 MT - but due to sci-fi magic the explosion can be more like 100 cubic meters of liquid antideuterium, which works out to be about 690 GT.
In one torpedo.
Plus, torpedoes can burrow through the surface of a planet, so going to the best depth to get the most damage.
Even disregarding the secondary source, the opening volley from the Tal Shiar/Obsidian Order fleet in "The Die Is Cast Pt.2" destroyed 30% of the surface of the planet they were attacking, and that wasn't a particularly large fleet by military standards (both organizations not being military, technically). Making an undefended planet uninhabitable seems almost trivial.