Life happens as you make other plans, the saying goes. And as Western militaries focus more and more on joint programs and interoperability, it's an important lesson to keep in mind.

The benefits for allies going joint are obvious: lower cost for programs and ease of communication during combat situations. And at this year's Farnborough International Airshow, jointness likely will be a hot topic once again.

But the fact that the show takes place just weeks after voters in the United Kingdom decided to leave the European Union underlines the fact that international programs are susceptible to political realities.

After all, the shock of a Brexit is still being sorted out, with the future of joint military development programs with other European nations now unclear – let alone the impact to UK industry.

A key British defense-trade association, perhaps fearful of losing a bit of its footing outside the comfortable framework of longstanding European Union trade agreements, already has appealed to future government leaders to send a strong signal of support for domestic jobs amid the uncertainty.

"It's not a panic situation," Paul Everitt, the chief executive of trade group ADS, Inc., is quoted as saying in a Defense News story in this issue. "We have got time, but it's important government gets on the front foot, it's not time for introspection. It's time for them to be relatively bold to ensure that key sectors understand there is a commitment to them and to make the UK competitive."

A less dramatic example of the challenges of joint development comes from the F-35 joint strike fighter, the most internationally shared development of a weapon system in history.

The chief of the US Air Force's integration office for the F-35, Maj. Gen. Jeffrey Harrigian, highlighted the challenge of coordinating among partner nations to operate the plane's Mission Data Files, as Defense News reported online.

The data included in those files amounts to something of a cheat sheet about the types of objects, like enemy weapons, pilots might find with their sensors during missions. The aircraft, which has been touted for its interconnectivity, in theory can transmit such data to nearby allied planes, whose pilots can then decide how to act on the information.

But in practice, officials are running into the problem that nations may be reluctant to employ their new F-35 weaponry based on intelligence provided by another.

"There are concerns about where the data comes from, can you trust it, that kind of thing," Harrigian told reporters in Washington. "There are nuances in some countries," he added. "We could offer them data, but we have to give them sources, and we can't give them sources, and they have a sovereign requirement to know where it came from so they know it's good."

Officials from international partners should use this year's Farnborough as a chance to take a sober, serious look at how international development programs are structured, and to asses the best way forward to achieve mutual benefit for all involved.

Being interoperable is important. Finding ways to bring costs down on development is important. Sharing information with partners is important. But in a post-Brexit Europe, companies and nations need to be cognizant that even the steadiest of industrial partnerships can be tested at any time.