On May 22, Israeli Air Force commander Amikam Norkin announced that its F-35I stealth fighters had flown on two combat missions on “different fronts,” showing as proof a photograph of an F-35 overflying Beirut. While details on those missions have not been released—apparently, they were not deployed in a massive Israeli air attack on Iranian forces in Syria that took place on May 9—this nonetheless apparently confirmed the first combat operations undertaken by any variant of the controversial stealth jet, which is currently entering service with the militaries of ten countries after undergoing over two decades of development.

In fact, Israel’s F-35I Adir—or “Mighty Ones”—will be the only F-35 variant to enter service heavily tailored to a foreign country’s specifications. There had been plans for a Canadian CF-35, with a different refueling probe and drogue-parachute to allow landing on short Arctic air strips, but Ontario dropped out of the F-35 program.

It has become a common practice to create custom variants of fourth-generation jet fighters such as the Su-30, F-15 and F-16 for export clients, made to order with local avionics, weapons and upgrades that suit a particular air force’s doctrine and strategic priorities. Today, Israel operates heavily upgraded F-15I Ra’am (“Thunder”) and two-seater F-16I Sufa fighters. Furthermore, Israel in particular hasn’t hesitated to modify aircraft it has already received fit its needs: for example, in 1981 it rigged its then-new F-15A Eagle air superiority fighters to drop bombs, and used these first-ever strike Eagles to destroy the Iraqi Osirak nuclear reactor.

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However, the Lockheed-Martin has mostly refused to allow major country-specific modifications to the F-35, despite the hundreds of millions of dollars foreign F-35 operators contributed to the aircraft’s development. There is, of course, an efficiency-based rationale, given the additional costs and delays of creating country-specific variants, and the fact that Lockheed is struggling to both produce F-35s fast and cheaply enough and build enough spare parts for the hundreds already in service.

Israel, however, managed to carve out an exception. Though not an investor in the F-35’s development, Tel Aviv was nonetheless quick to sign on to the program with an initial order of fifty. It also negotiated a favorable deal in which billions of dollars worth of F-35 wings and sophisticated helmet sets would be manufactured in Israel, paid for with U.S. military aid. Furthermore, depot-level maintenance will occur in a facility operated by Israeli Aeronautics Industries rather than at a Lockheed facility abroad.

The first nine F-35s entered operational service in December 6, 2017, with the 140 “Golden Eagles” Squadron, based at Nevatim Airbase near Be’er Sheva. Six more should arrive in 2018. Israel will eventually activate a second squadron at Nevatim, and retains the option for an additional twenty-five F-35s to form a third squadron, likely based elsewhere. However, recent reports suggest a third squadron may postponed for a decade in favor of buying additional F-15Is, which trade the F-35’s stealth for greater range and payload. Israel has paid a high price of between $110 to $125 million per F-35 for its initial order, but in the future unit cost will supposedly decline to around $85 million.

The first nineteen stealth jets received by Israel will actually be standard F-35A land-based fighters, while the following thirty-one will be true F-35Is modified to integrate Israeli-built hardware. However, most media sources have taken to labeling all of them as F-35Is, and it does appear even the initial batch will be retrofitted with an open-architecture Israeli Command, Control, Communications and Computing (C4) system.

The Lightning’s sophisticated flight computer and ground-based logistics system has become a matter of contention with many F-35 operators. Foreign air forces would like to have greater access to the F-35’s computer source codes to upgrade and modify them as they see fit without needing to involve external parties—but Lockheed doesn’t want to hand over full access for both commercial and security-based reasons.

Israeli F-35Is uniquely will have an overriding Israeli-built C4 program that runs “on top” of Lockheed’s operating system. One of F-35’s key capabilities come from its superior ability to soak up data with its sensors and share it with friendly forces. Compatibility with datalinks used by friendly Israeli air and ground forces is thus an important aspect from Israel’s perspective as it tracks the position of hostile surface-to-surface rocket launchers and surface-to-air missiles systems.

The new system will also allow the IDF to install Israeli-built datalinks and defensive avionics systems such as radar-jamming pods. An official told Aviation Week the IAF expects the advantages of the F-35’s low radar cross section will be “good for five to ten years” before adversaries develop countermeasures. There already exist methods for detecting stealth fighters, including long-range infrared sensors, electromagnetic sensors, and low bandwidth radars (though all have significant limitations), and more exotic technologies such as quantum radar are also under development.

Thus, the IDF particularly values the flexibility to install “plug-and-play” defensive countermeasures such as jamming pods as they become relevant and available. It so happens the Israeli firms Elbit and Israeli Aerospace Industries are major developers of such systems. However, due to the F-35’s highly “fused” avionics, such plug-and-play support needs to be built both into F-35 software and apparently even the airframe. The add-ons will be installed in special apertures in the lower fuselage and leading edge of the wings—presumably, features only in the later production F-35Is that arrive in 2020.

Israel is also developing two different sets of external fuel tanks to extend the F-35’s range. The first will be non-stealthy 425-gallon underwing tanks developed by a subsidiary of Elbit—these could be dropped when approaching enemy airspace (the pylons holding the drop tanks would reportedly detach as well so as not to compromise stealth), or used for missions in which stealth isn’t necessary. Further down the line, IAI wants to co-develop with Lockheed bolt-on conformal fuel tanks which “hug” the F-35 airframe so as not to compromise stealth and aerodynamics.

The F-35I will also be certified to carry major Israeli-developed weapons systems in its internal weapons bay, notably including the Python-5 short-range heat-seeking air-to-air missile, and the Spice family of glide bombs, which combine electro-optical, satellite and man-in-the-loop guidance options for greater targeting versatility and have a range of up to sixty miles.

However, country-specific F-35 weapons capabilities are not unique to Israel. British Royal Air Force and Navy F-35s will be compatible with the Meteor and ASM-132 air-to-air missile, while Norway and Australia’s Lightning IIs will be able to carry the Norwegian Naval Strike Missile, reflecting the importance of the sea-control mission for these nations. The United States even would like its NATO partners to purchase F-35s specially modified to deploy B-61 nuclear bombs.

The Adir and Israeli Strategy

Norkin’s announcement of F-35 operations was as much a part of Israeli strategy as the actual deployment of the fighters. Tel Aviv wants potential adversaries (chiefly, Iran, Syria, and Hezbollah) to know that its fighters have already proven capable of infiltrating the airspace of neighboring countries, and that its stealth jets could at any moment launch an attack that may go undetected until the first bomb strikes a target.

The F-35 has been criticized for its mediocre flight performance compared to earlier fourth-generation jets, meaning that it would be at a disadvantage in a short-range ai dogfight against enemy fighters. Supporters argue that the F-35 would leverage its stealth, sensors and long-range missiles to avoid getting that close to more agile opponent in the first place, and that the platform is really optimized more for striking targets in defended enemy airspace.

The strike emphasis, however, is just fine with the Israeli Air Force, as since 1948 it has historically mostly trounced its opponents in air-to-air combat, but suffered heavy losses to ground-based air defenses in the 1973 Yom Kippur War. Since then, Israel jets have continued to face, and mostly defeat, hostile SAMs in scores of raids launched into Lebanon and Syria, though in February 2018 it suffered its first combat loss of a fighter in decades when Syrian S-200 missiles downed an Israeli F-16. Since 2017, there have been rumors of the F-35s involvement in these raids, though most of these rumors were likely inaccurate due to the risk of losing an airframe over hostile territory at this stage.

Prime Minister Benjamin Nethanyahu, in power since 2009, clearly favors using military force to suppress Iran’s nuclear research program, having opposed and undermined negotiated settlements. While Tel Aviv basically wants the United States to carry out such an attack, the F-35 makes an Israeli attack on Iran more practical.

However, Israeli aircraft would have to fly through Turkey, or either Jordan and Syria and then Iraq to reach Iranian aerospace over six hundred miles away—and remember, key targets will likely be much further from the border. This also happens test the range limit of most combat-loaded fourth-generation fighters, meaning they would need conspicuous aerial tankers to make the raid viable. Furthermore, Israeli warplanes would have to disable or destroy Iranian air defenses, which would require additional time and aircraft.