A continued Pentagon refusal to integrate Israeli systems into the stealth Joint Strike Fighter will likely cause delays in the arrival of the advanced fighter jet to Israel, senior defense officials and IDF officers told The Jerusalem Post. In July, the Defense Ministry submitted an official letter of request to the Pentagon to purchase its first squadron of 25 F-35 stealth fighter jets, but officials said Tuesday that the target for a contract - the beginning of 2010 - would likely not be met. "The negotiations are still ongoing and we do not even know yet what the price of the aircraft will be," said a top officer involved in the negotiations. Estimates are that the plane will cost around $100 million. Also known as the F-35, the JSF will be one of the most-advanced fighter jets in the world and will enable Israel to phase out some of its older F-15 and F-16 models. The JSF is manufactured by Lockheed Martin. The first stage of the deal will be the purchase of 25 aircraft which will comprise the first Israeli F35 squadron. In a later stage, the IAF plans to purchase an additional 50 aircraft, some of them with vertical take-off and landing capabilities. In the negotiations with the Pentagon, Israeli demands have focused on three issues - the integration of Israeli-made electronic warfare systems into the plane, the integration of Israeli communication systems and the ability to independently maintain the plane in the event of a technical or structural problem. The British have made similar requests and according to a recent report in the Daily Telegraph is also seeking independent maintenance capabilities as well as access to some of the more classified technologies. The Israel Air Force had initially hoped to sign a letter of agreement in the coming months, but officials said that until the differences were resolved and a price was determined the contract would be postponed. If that happens, the arrival of the aircraft - initially slated for 2014 - will also be pushed off. "The plane is not yet operational and is not even in production," a senior defense official said. "The first military to get the plane will be the US, then the UK and then Israel." Commenting on the price, the official said that if the plane crossed the $100 million mark Israel would have to seriously reconsider how many aircraft it will purchase.