In 1970 Chief of Naval Operations Admiral Elmo Zumwalt accelerated the development of Harpoon as part of his "Project Sixty" initiative, hoping to add much-needed striking power to U.S. surface warships such as the Ticonderoga-class cruiser.

[5] The Harpoon has also been adapted for carriage on several aircraft, including the P-3 Orion, the P-8 Poseidon, the AV-8B Harrier II, the F/A-18 Hornet and the U.S. Air Force B-52H bombers.

[6] The Harpoon was purchased by many nations, including India, Japan, Singapore, South Korea, Taiwan, the United Arab Emirates and most NATO countries.

The Spanish Air Force and the Chilean Navy are also AGM-84D customers, and they deploy the missiles on surface ships, and F/A-18s, F-16 Falcons, and P-3 Orion aircraft.

[13] The Republic of Singapore Air Force also operates five modified Fokker 50 Maritime Patrol Aircraft (MPA) which are fitted with the sensors needed to fire the Harpoon missile.

At least 339 Harpoon missiles were sold to the Republic of China Air Force (Taiwan) for its F-16 A/B Block 20 fleet and the Republic of China Navy, which operates four guided-missile destroyers and eight guided-missile frigates with the capability of carrying the Harpoon, including the eight former U.S. Navy Knox-class frigates and the four former USN Kidd-class destroyers which have been sold to Taiwan.

[14] This version featured a larger fuel tank and re-attack [further explanation needed] capability, but was not produced in large numbers because its intended mission (warfare with the Warsaw Pact countries of Eastern Europe) was considered to be unlikely following the Dissolution of the Soviet Union.

[citation needed] In production at Boeing facilities in Saint Charles, Missouri, is the Harpoon Block II, intended to offer an expanded engagement envelope, enhanced resistance to electronic countermeasures and improved targeting.

[19] India acquired 24 Harpoon Block II missiles to arm its maritime strike Jaguar fighters in a deal worth $170 million through the Foreign Military Sales system.

[20] In December 2010, the Defense Security Cooperation Agency (DSCA) notified U.S. Congress of a possible sale of 21 additional AGM-84L Harpoon Block II Missiles and associated equipment, parts and logistical support for a complete package worth approximately $200 million for the Indian Navy's P-8I Neptune fleet.

[25][26] In April 2020, DSCA approved the sale of 10 AGM-84L Harpoon missiles along with containers, spare and repair parts, support and test equipment for the P-8I fleet to the Indian Navy at a value of $93 million.

[6] In early 2018, the U.S. State Department approved the sale of Harpoon Block II to the Mexican Navy for use on their future Sigma-class design frigates, the first of which is being built by Damen Schelde Naval Shipbuilding.

The Block II+ incorporates an improved GPS guidance kit and a net-enabled data-link that allows the missile to receive in-flight targeting updates.

After experiencing an increase in the scope of required government ship integration, test and evaluation, and a delay in development of a data-link, the Harpoon Block III program was canceled by the U.S. Navy in April 2009.

[36] Boeing claims the Block II+ ER is superior to the Naval Strike Missile through its improved turbojet giving it greater range and active radar-homing seeker for all-weather operation, as well as a lighter but "more lethal" warhead.

A Notice to Mariners had been issued warning of the danger, but Jagvivek left port before receiving the communication and subsequently strayed into the test range area, and the Harpoon missile, loaded just with an inert dummy warhead, locked onto it instead of its intended target.

The UGM-84A undersea-launched Harpoon version was retired from U.S. Navy service in 1997, leaving the U.S. submarine force without an anti-ship missile, a capability that is not planned to be reintroduced until the Block IV Tomahawk is modified with a moving target maritime attack feature in 2021.

Robert Hewson, editor of Jane's Air Launched Weapons, pointed out that the Harpoon is not suitable for the land-attack role due to deficiency in range.

In 2020 its manufacturer Boeing won two major contracts for supplying Harpoon missiles to Saudi Arabia and six other partner nations under a $3.1 billion deal.