LE BOURGET, France — As European defense firms drum up publicity about the sixth-generation fighters they plan to build, Lockheed Martin executives promoted the F-35 as the proven fifth-gen option that could blur the lines with sixth-gen planes as it is upgraded into the 2020s and beyond.

“It’s a compliment to the F-35 that many countries are looking to replicate fifth gen and then extending that to sixth gen,” Michele Evans, Lockheed’s head of aeronautics, told Defense News at the Paris Air Show on June 19. “I think it really does reflect on the value of what F-35 is bringing to the pilots and the battlespace. In terms of technology, we’re not going to let F-35 go static.”

During a Monday briefing, Lockheed laid out a series of upgrades that could be adopted during the jet’s “Block 4” modification phase in the mid 2020s.

Fundamental to Block 4 is the upcoming “Tech Refresh 3” package of IT upgrades, including a new integrated core processor with greater computing power, a panoramic cockpit display and an enhanced memory unit, said Greg Ulmer, Lockheed’s vice president and general manager of the F-35 program. The company intends to incorporate TR3 in F-35s starting in Lot 15, with those jets rolling off the production lot in 2023.

Also in TR3, Lockheed plans to move to an open-architecture backbone for the F-35, which will allow it to more quickly boost the jet’s capabilities with new software.

“You’ll see year over year over year we’re going to have an incremental update,” Ulmer said. “Rather than biting it all off [at one time] and waiting for a big-bang tech insertion, we’re going to trickle that out.”

× Fear of missing out? Sign up for the Early Bird Brief, the defense industry's most comprehensive news and information, straight to your inbox. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

Some of the modifications that could become available in Block 4 include capabilities like conformal or external fuel tanks that could extend the jet’s range by more than 40 percent, or the auto-ground collision avoidance system that is set to roll out this month — six years earlier than expected.

But other potential upgrades might lead to an F-35 that blurs the line between a fifth-generation fighter — characterized by stealth and sensor fusion — and a sixth-generation one, which at least currently is seen as having advanced network capabilities that could give the pilot control over external weapons, drones and sensors.

The U.S. Air Force has been upfront about wanting to team the F-35 with low-cost attritable drones outfitted with artificial intelligence. Attritable aircraft are inexpensive enough for to be replaced if they are shot down or damaged, allowing operators to take a greater amount of risk while using them.

While the F-35 program currently does not have manned-unmanned teaming as part of its program of record for Block 4, Ulmer said the technology is achievable.

“I think the F-35 is very well-positioned for manned-unmanned teaming. The data sensor fusion approach to the airplane as well as our relationship with our brethren at Skunk Works, I think we’re very well-aligned,” he said, referring to Lockheed’s secretive advanced development arm.

Ulmer pointed to missile defense as another potential use for the F-35.

“We’ve done some experimentation here and have seen some very strong results as well, and that will only improve with the TR3 capability of the airplane,” he said.

While Ulmer didn’t elaborate, the Defense Department is studying whether to outfit the F-35 with a weapon that would allow it to shoot down cruise missiles or intercontinental ballistic missiles. Even if the Pentagon opts not to go in that direction, an F-35 might be able to track ICBMs — as it demonstrated during simulated exercises in 2014 — or pass along targeting information to other assets that then could intercept it.

Multidomain command and control is another potential area of expanse. Again, Ulmer did not provide many details, but acknowledged that Skunk Works has conducted experiments with how the F-35 gathers and shares information, and that they have seen “very strong results.”

Asked whether Lockheed could offer an upgraded F-35 to the U.S. services in sixth-generation fighter competitions rather than a completely new airframe, Evans acknowledged that “it’s definitely something Lockheed is looking at.”