Why a large ASW frigate still needs general-purpose defenses

Does an anti-submarine frigate need meaningful anti-surface and missile-defense weapons?

Yes; large frigates face missile threats from submarines, surface ships, and aircraft and must protect both themselves and the convoy.

A six- or seven-thousand-ton anti-submarine frigate cannot specialize so narrowly that it lacks anti-surface and air-defence capability. The Type 054A example combines a medium-range surface-to-air missile, jamming and decoys, a 76 mm gun, underway replenishment, and substantial anti-surface weapons. Even coastal submarines of only a few hundred tons may launch anti-ship missiles, but hostile surface combatants remain at least as direct a danger. Maritime patrol aircraft such as Nimrod can also deliver air-launched Exocet, potentially against the convoy instead of the escort. The frigate therefore needs layered self-defence and enough general-purpose armament to suppress surface threats while continuing its anti-submarine mission. Modern ASW escort protects a formation across several domains rather than fighting a duel only below the waterline.