Washington (CNN) -- The Defense Department reviewed its most expensive weapon Monday, the F-35 Joint Strike Fighter.
A defense acquisition board, known as a DAB, met behind closed doors at the Pentagon to examine the project that has forced repeated changes to deadlines and cost estimates.
The jet is being designed simultaneously for different take-off and landing capabilities for the Air Force, Navy and Marines. U.S. allies including Britain and Australia are assisting in its development.
There was no statement released at the conclusion of the DAB meeting Monday. One source familiar with the proceedings, but not authorized to speak publicly, said the session lasted three hours.
The Monday meeting was informational and preliminary, the source said, and was expected to be followed by another session in coming weeks, once more information has been compiled.
Pentagon spokesman Geoff Morrell said last week that any major decisions about the future of the project would not come now but instead would be part of the larger discussions about defense spending for the 2012 budget.
Some estimates put the cost of the F-35 at more than $380 billion, making it the Pentagon's most costly weapons program.
Defense Secretary Robert Gates fired the person in charge of the program earlier this year and put Vice Adm. David Venlet in charge.
Pentagon spokesman Morrell said last week that Venlet is now leading what Morrrell called now a "deep dive" review of the Joint Strike Fighter program.
"There have been troubles with this program. We've acknowledged that for -- frankly, for the last couple of years," Morrell said at a Pentagon briefing. "And the secretary in February undertook a major restructuring of this program."
And Morrell said despite what he called newly discovered "issues of concern," that Gates continues to support the program. "This program is -- this will be the backbone of our TACAIR [tactical air] for decades to come. So it is of vital importance to this department. The secretary has believed that for some time. He continues to believe that," Morrell said.
"What we found is we have more software code to be written than we had originally thought. So that's just an example of having, you know, gone under the hood yourself and taken a look at the engine firsthand, that we have discovered additional things that need to be done to get ultimately to where we want to be," Morrell said.
"This is 120 people not taking anybody's word for anything but saying to them, 'Show me the money, show me the proof, show me the data, don't give me your version of the world, I want to see your version of the world.' And I think, as a result, we feel as though we have a much better understanding, including some new issues, of where we stand with this program and what might need to be done as a result of that."