A non-Federation world of about 5,000 people which Admiral Reeger orders destroyed from orbit while hunting a cloaked raider in the Strange New Worlds fourth-season episode Orders of Magnitude.
Argos II is an inhabited planet outside the Federation. In Orders of Magnitude, from the fourth season of Strange New Worlds, the Enterprise follows a radiation trail to it while running silent, in pursuit of a cloaked ship blamed for a massacre.
Admiral Reeger, who has taken command and is directing the hunt, decides without proof that the planet must be the raider's base. He issues General Order 24, the command to lay waste to a planet's surface, which here would kill some 5,000 people.
James Kirk, serving as first officer, objects and is confined. He then claims to have sabotaged the phasers so that firing them would destroy the ship, a bluff that goads Reeger into a rage, and Doctor M'Benga declares the admiral unfit and relieves him. The order is never carried out and the cloaked ship gets away. General Order 24 itself comes from the original series episode A Taste of Armageddon.