Israel has become the first foreign nation to place its stamp of approval on the fledgling F-35 Lightning II warplane being developed by Lockheed Martin Aeronautics Co. in Fort Worth.

The Pentagon has formally notified Congress that it plans to sell up to 75 F-35s to Israel, a deal potentially worth up to $15.2 billion to Lockheed and the legion of contractors working on the program.

In a news release issued Tuesday, the Defense Security Cooperation Agency said Israel has requested to buy 25 F-35A joint strike fighters like those that will be produced for the U.S. Air Force.

In addition, Israel wants an option to buy 50 more jets, either the F-35A models, which take off and land conventionally, or the planned F-35B variant, which would make short takeoffs and vertical landings.

The order is the first in quantity for the F-35, which is still in the early stages of development. Delivery of planes to the Israelis is not likely before 2014, after most of the scheduled U.S. testing is completed.

Israel's endorsement of the F-35 long before most flight testing is potentially valuable. Israel's air force is "the most closely watched and highly regarded outside the U.S.," said Richard Aboulafia, aerospace industry analyst for the Teal Group consulting firm in Fairfax, Va.

The planned sale to Israel is no surprise.

The country submitted a letter to the U.S. government in May formally requesting to buy planes. Pentagon officials, including Air Force Gen. Charles Davis, the military director of the program, were in Israel last week on a widely reported mission working out details.

Dan Darling, a Middle East analyst with Forecast International, said Israel, which initially planned to buy 100 F-35s, will almost certainly buy all 75 and could well ask for more before its recently implemented five-year defense plan is up.

"I can't see them not picking up that option," Darling said.

Lockheed officials declined to comment directly on the proposed sale, saying it was government-to-government process. The company did release a statement that said:

"As the first potential Foreign Military Sale of the F-35, this would be an important first step in expanding interest in the Joint Strike Fighter beyond the U.S. [government] and eight international F-35 Partner Nations."

The notification gives Congress 30 days to reject the sale, which rarely happens. Israel, the Pentagon and Lockheed would then have to negotiate a final contract.

The planned sale comes at an opportune time for the program. In recent weeks the F-35 has been the target of considerable negative news coverage, mostly overseas, and several European governments once thought to be firm future buyers are being pressured to buy competing aircraft.

"The F-35 has gotten its share of bad press lately, so this really helps," Aboulafia said. "It's kind of uncertain why there haven't been more concrete orders."

Although Israel is placing the order, Darling said U.S. taxpayers will pick up most of the tab through annual foreign-aid grants targeted specifically to purchases of U.S. weapons systems. U.S. arms aid financing for Israel totaled $2.4 billion in 2008 and will rise to $3.1 billion annually from 2012 through 2018.

Israel is not one of the eight foreign partner nations that have invested large sums of money in the F-35 development program, although it did contribute $20 million in 2003 to gain access to information from the development process.

None of the original eight nations have yet to commit to firm production orders, although Britain and the Netherlands are purchasing a total of three test aircraft.

Lockheed and the Pentagon are negotiating with the partner countries over a plan that would allow them to order early production aircraft at prices lower than they might otherwise get.

The first F-35 test aircraft completed its 54th test flight Monday, said Lockheed spokesman John Kent. It is scheduled to depart today for Edwards Air Force Base in California for more extensive flight testing.

The second aircraft, the first F-35B, completed 14 test flights before it was parked two weeks ago. The aircraft will undergo a series of major upgrades before it can begin vertical flight testing early next year.