Citing budgetary constraints, a Pentagon official has ruled out the prospect of installing Israeli-made electronic warfare suites in the F-35 Joint Strike Fighter, but the Ministry of Defense struck a more optimistic tone, telling The Jerusalem Post on Wednesday that talks on installing further Israeli systems were still on. According to a Reuters report released earlier in the day, US-built models of the jet would incorporate Israeli-made data links, radios and other command and control equipment, but would exclude an Israeli-made electronic warfare suite due to the high cost of integrating the system into the plane. Israeli systems "have already been installed in the F-35," the Ministry of Defense said in a statement. "We are holding further discussions to install further systems," the statement added. Reuters cited Jon Schreiber, of the Pentagon's F-35 program office, as saying that the installation of further Israeli systems "is not going to happen," and that the US "system will meet their requirements with some tweaking, and I think they're starting to come around to that realization themselves." "They have pretty tight budget constraints, and we're attempting to fit their requirements into their budget," Schreiber was quoted as saying. The F-35 is slated to begin replacing the F-16 fighter jet in the US and elsewhere over the next five years. With its reported firepower, stealth and cutting edge technologies, the jet is described by its maker, Lockheed-Martin, as the most "lethal, supportable and survivable aircraft ever to be used by so many war fighters across the globe." Talks continue between Israel and the US over the purchase of 25 jets at $150 million each, and Pentagon approval for the deal has been received, although an official order has not yet been made. Israel routinely asks its defense companies, such as Elbit, Rafael Advanced Defense Systems and Israel Aerospace Industries to install technological variations into imports of American fighter jets. "As soon as we purchase the aircraft, we replace some of the systems on the spot, and some later on," Maj-Gen. (Ret.) Herzl Bodinger, former head of the Israel Air Force, told the Post. Some of the systems Israel habitually installs include radio communications and Electronic Countermeasures (ECM) systems, Bodinger said. In some cases, Israel replaces the missile system too. "If the air force wishes to install an Israeli-made missile on the plane, other systems need changing," he added. "You can't just attach a new missile on the plane, you have to change things so that the plane's computer can communicate with the new missile. It's like buying a new computer program," Bodinger added. While the changes usually made by Israel were not sweeping, they did increase the cost of the jet, Bodinger said. The Israeli changes have "never been a source of any tension with the Americans," Bodinger said. "Most of the time the Americans make the changes for us. We put a few things in, but the whole plane was made by them. The Americans make excellent jets. I only have good things to say," he added.