The AGM-84 Harpoon is a long-range anti-ship missile usable by any aircraft in either game except the F-22 Raptor, the A-10 Thunderbolt and the F-15C Eagle. The SLAM variant also appears in aimStrike!.
The Harpoon is extremely effective against warships: It has longer range than any of their SAMs, and can destroy any vessel in the game in one hit, with the exception of the Kuznetsov, which takes two to destroy.
The F-35 JSF is very useful as a naval assault fighter as it can mount four Harpoons, so it can engage four vessels (two if both ships are Kuznetsov) while remaining out of their range, and can easily resupply from an Aicraft Carrier. The Harpoon has long range, allowing a player to slowly approach a warship, fire away, then retreat before entering hostile missile range.