Saudi Arabia recently expressed interest in upgrading the avionics and weapons payload for most of its F-15 fleet, raising the issue with both the State Department and the Boeing Corporation (but has yet to enter into formal negotiations over the issue). In 1981, Saudi Arabia procured 91 F-15C/D fighter-jets from the United States, of which only about 80 remain in service. The upgrade allegedly would not include either the engine or the planes' structure.
Saudi F-15s have also made the news recently, for more ominous reasons. The Israelis contend that Al Qaeda tried to recruit Saudi Arabian Air Force pilots for attacks in Israel from their nearby airbase at Tabuk. At the beginning of October, IDF Commander-in-Chief Moshe Ya'alon' told with the media that the plans were similar to those executed in the United States on September 11, 2001, using either F-15 jets or civilian aircraft. It's not like Saudi pilots haven't done strange things in the past. An asylum-seeking Saudi F-15 pilot flew his aircraft to Sudan in November 1990 (although the plane was later returned.) Now just imagine if, in pursuit of nuclear weapons, Saudi Arabia was able to acquire weapons that could be carried by their F-15s. 

Israel complained to the U.S about the presence of the American-supplied jets at Tabuk, which they contend contravenes promises America made over the years about how the planes would be deployed. The Israelis claim that the F-15s were transferred in March to Tabuk, on the eve of the war in Iraq to protect them against Iraqi air or missile attack. The kingdom has since refused to return them to their original bases in central and eastern Saudi Arabia, despite the fall of Saddam Hussein in April. Prince Khaled confirmed to the Saudi based Arab News Agency that they had F-15s stationed in Tabuk, and that they would "keep them there because they are deployed inside our territory.'' So far, America has opted to remain silent. - Adam Geibel