The Israeli Defense Ministry is talking with the Pentagon about buying Boeing's F-15E1 because of delays in developing Lockheed Martin's F-35 Joint Strike Fighter, Israel's first choice for its next major fighter purchase, The Jerusalem Post reported Monday.

The Israeli air force took considerable interest in the F-15E1's 80-minute maiden flight over St. Louis at the weekend.

"While Boeing is still reportedly awaiting Pentagon approval to export the plane, Israel has already held a number of initial discussions regarding the plane and its capabilities," the Post reported.

The Israelis haven't reached a decision on whether to stick with the F-35, despite the 2-year delay in its development that was announced by the U.S. Department of Defense March 11 and the possibility that there could be further problems.

The delays mean the F-35 wouldn't be ready for operational deployment until 2015 instead of 2013, well past the date the Israelis wants to acquire new strike aircraft.

On top of the delays, the cost of the aircraft has risen from $50 million per plane when the program began in 2002 to a stratospheric $112 million now. This was attributed to overruns, inflation and the increased cost of materials.

But, some industry sources say, the cost could swell to around $150 million when revised estimates are completed.

The Israelis have been dismayed by the ever-rising price tag on the F-35. They have sought to limit this to around $100 million per plane but that seems to be out of reach as development costs soar.

For the Israelis, the advanced version of the F-15 Eagle has been seen as an alternative to the ill-starred F-35 for some time, both in terms of delivery schedule and cost.

Boeing unveiled the Silent Eagle in March, about the same time the Department of Defense announced the F-35 program's problems.

It will reportedly cost around $100 million per plane, which conforms with the ceiling the Israelis have put on acquiring a fifth-generation fighter.

The new F-15 configuration reportedly includes a stealth capability but that's only effective in evading the radars carried by hostile aircraft but not by ground-based radar systems.

Other improvements include adapting the F-15's conformal fuel tanks to carry weapons inside the fuselage rather than externally, thus reducing the radar signature.

One of the functions tested during the F-15 Silent Eagle's weekend flight was opening and closing its left side conformal weapons bay that contained an AIM-120 air-to-air missile, which wasn't fired.

"The Silent Eagle demonstration validated our initial engineering design approach," said Boeing's F-15 Development Programs Director Brad Jones.

"This flawless flight allows us to move into the next phase. In the next couple of weeks we'll ferry the F-15E1 to the test range and launch an AIM-120," Jones said.

The Israelis have yet to sign any contract for the F-35. This has been held up in part because of another obstacle, Israel's demand any F-35 it buys be equipped with indigenous electronic and weapons systems.

Jane's Defense Weekly reports the Americans have approved the installation of Israeli electronic warfare systems,but no decision has yet been made concerning Rafael Advanced Defense Systems' Spice guided bomb unit and Python-5 air-to-air missile.

The Israeli air force wanted to buy an initial batch of 25 F-35s -- enough or one squadron -- with delivery in fiscal 2012, with an option for 50 more.

Israel has 27 F-15I Ra'ams and 102 F-16I Sufa ground-attack fighters, as well as 72 F-15 A/B/C/D and 224 F-16 A/BN/C/D fighter and strike variants.

The Ra'ams and Sufas comprise the air force's strategic long-range strike force which would carry the main burden in any pre-emptive Israeli strikes against Iran's nuclear infrastructure.

While Israeli is showing some interest in possibly acquiring F-15 Silent Eagles, it is seeking to persuade the Americans from selling up to 72 advanced-model F-15s to Saudi Arabia.

The defense ministry claims Israel's qualitative edge over its adversaries, which successive U.S. administrations have pledged to maintain, would be eroded if the Saudis got their hands on such aircraft.