Seems that Lockheed-Martin is getting low on cash and may have to borrow money to pay their suppliers. There isn't an agreement with the US DoD on how much the next batch of F-35s should cost. You can read the full article from the WSJ here:
Lockheed Jet Takes Toll on Its Cash -- WSJ - NASDAQ.com
A bit of a "Catch 22" situation for the current US government and taxpayers thanks to the way the contract was setup from the get-go.