Complex sentence: Many air-to-surface missiles can be used against both ships and land targets, although some must be modified to perform a different role; for example, the Standoff Land Attack Missile is a land-attack version of the Harpoon.
Split into simpler sentences: Many air-to-surface missiles can be used against both ships and land targets, although some of them have to be modified to perform both roles effectively. For example, the Standoff Land Attack Missile is a land-attack version of the Harpoon.