F-35I Aldir

The Lockheed Martin F-35 Lightning II Israeli procurement is the result of an agreement for the government of Israel to purchase the Lockheed Martin F-35 Lightning II for the Israeli Air Force as the F-35I "Adir" (Hebrew for "Mighty One" or "Awesome"). The first nine F-35s became operational with the Israeli Air Force in December 2017.

In July 2011, it was reported that the U.S. had agreed to allow Israel to install its own electronic warfare systems and missiles in its F-35s in the future.
In 2012 Lockheed was awarded a contract to make changes to the first Israeli F-35s to allow the installation of Israeli electronic warfare equipment produced by Elbit Systems.
This equipment will use "specific apertures in the lower fuselage and leading edge".
Israel also plans to install its own indigenously produced guided bombs and air-to-air missiles in the F-35's internal weapons bay.
Benni Cohen compared the Israel Aerospace Industries command and control system to an iPhone App that would run on top of the central avionics.

Israel is the only country that the United States has permitted to heavily modify the F-35's core systems to suit its specific strategic and operational needs.

The most significant difference lies in the aircraft's electronic warfare capabilities. While the standard F-35A has a highly advanced EW system, the US allowed Israel to integrate its indigenous EW suite over the core architecture. This includes advanced jamming systems, electronic support measures (ESM), and countermeasures developed by Israeli defense companies (like Elbit Systems and Israel Aerospace Industries). This allows the Adir to better counter specific regional threats, such as advanced Russian-made air defense systems deployed in the Middle East.

Israel integrated its own custom C4I (Command, Control, Communications, Computers, and Intelligence) systems into the Adir. This "plug-and-play" system allows the F-35I to seamlessly share data and communicate securely with the rest of the Israeli Defense Forces (IDF) network, including older legacy fighters like the F-15I and F-16I, as well as ground and naval units.

While the F-35A primarily carries US-made munitions, the F-35I is modified to carry Israeli-developed weapons internally to maintain its stealth profile. This includes munitions like the Rafael SPICE autonomous air-to-surface glide bombs, Python air-to-air missiles, and other specialized precision-guided munitions designed for the IDF's specific strike profiles.

Because Israel faces threats at significant distances (such as in Iran or Yemen), the IDF has worked on extending the range of the F-35I. Reports indicate that Israel has developed specialized external drop tanks for the Adir. While carrying external tanks temporarily compromises the aircraft's stealth, they can be dropped before entering highly contested airspace, allowing the F-35I to conduct long-range strikes without relying entirely on aerial refueling.

More info:

• Wikipedia - F-35I