The eight foreign countries and the United States are "all in different places" in terms of economic stability, particularly those in Western Europe, Air Force Secretary Michael Donley said on Thursday.
However, these realities have not swayed any of those countries from their commitments to the JSF, which is now the most expensive military weapons program in Pentagon history.
Those countries "have a good bead" on what steps they need to take to keep the JSF program going in their own governments, Donley said.
His comments echoed those made by DOD spokesman George Little during a Tuesday press conference at the Pentagon.
The Air Force chief noted that countries outside the original nine JSF members have approached DOD with interest about participating in the program.
Japan is the latest nation to join the group. It chose the JSF as its new fighter jet last December.
South Korea is also rumored to have expressed interest in buying the next-generation fighter.
But recent difficulties experienced by half of the original JSF coalition members could have a chilling effect on that growing interest.
A scathing report claiming Canadian defense officials failed to inform top government decision makers "of the problems and associated risks" with buying the F-35 has Ottawa questioning whether it will continue with the JSF.
Draconian defense spending cuts in the United Kingdom already have London throttling back its planned purchases of the F-35.
Officials from German Chancellor Angela Merkel's administration on Tuesday ruled out Spain as the next European Union member to need a bailout, according to Reuters.
But it is widely assumed that Italy will be the next country to join Greece and Ireland as the recipient of an EU-financed bailout.
All these factors could lead to a number of JSF partners dramatically ramping down their participation on the fighter or leaving the program altogether.
That said, allowing those countries to work their way through those fiscal challenges while keeping them on board the JSF is a concern, Donley noted.
But dealing with those types of issues, while trying to get the U.S. fleet of F-35s flying is just "part of what managing an international program is all about," he said.