LONDON — There is no system in place to strip Canada of its F-35 industrial participation should the government in Ottawa go through with threats to drop the fifth-generation fighter, according to a top US official.

Speaking in London ahead of the Farnborough International Airshow, Frank Kendall, the Pentagon's top weapons buyer, said there is "no process in place" for what happens to Canada's work share on the F-35 program if it should not buy the jet. He added that prime contractor Lockheed Martin would have to work with the other partner nations to figure out if or how that work share could be reapportioned.

Liberal Party Prime Minister Justin Trudeau pledged as part of his election campaign to cancel plans to buy 65 F-35s, which the previous Canadian government had agreed to. Trudeau says the jets are too expensive for Canada's budget. Instead, the government is looking at buying 20 to 30 F/A-18 Super Hornets, produced by Boeing, as an interim solution.

However, Canada is an industrial partner on the F-35 program, with an estimated 110 Canadian companies expected to make CA$825 million (US $632 million) in contracts over the lifespan of the program. And as Trudeau has continued to trash the Joint Strike Fighter, Lockheed Martin has been explicit that it will look to move that industrial participation elsewhere if Canada does, indeed, drop the jet.

Canadian officials have hit back that there is no legal requirement that the nations participating in the industrial base work must also buy the jet, but the work-share decisions are made by Lockheed Martin, and the US government is not giving signs it would lean on the company to allow Canada to keep its business.

Or, as Kendall put it: "It is an economic partnership for each of the partners to have work share, and I think there would be pretty strong reaction amongst the rest of the partners to continuing to provide work share to a country that's not participating in buying aircraft."

Just how moving work share from Canada to other partners would work, however, is unclear.

"There is no written agreement, there is no standard process we have in place to follow in the case of someone withdraws," Kendall explained Sunday. "There is no, I'll call it, a rule. There's no rule in place that if you withdraw you automatically lose industrial content, but it's a consequence that I think a lot of people will want to talk about if someone pulls out."

What appears likely, he said, is that if work share was allocated elsewhere those parts would be slipped into the supply chain down the line, rather than put into existing production jets — in other words, there should be no slowdown on production despite needing to certify new industrial parts.

"I don't think we would stop any existing work that's in place. We're not going to cancel any contracts that are ongoing, that would not make any sense," Kendall said. "So it is future orders that I think would be in question."

Of course, the F-35 decision is not final. And while Trudeau's government initially signaled that the F-35 would not even be allowed to recompete for Canada's fighter contract, there are hints that may no longer be true.

Speaking last week at the Royal International Air Tattoo in England, Lt. Gen. Chris Bogdan, the F-35 program head, said there is "encouraging news" on that front.

"I think they're going to open up their aperture and look at multiple different options," Bogdan said. "And we think that's good because we think that the F-35 will fare very well looking across what else is out there. But that's a Canadian decision."

The main argument against the F-35 in Canada has been the cost, but Bogdan expressed confidence that there is steady progress being made in that arena.

"They’re going to have to do their due diligence. We now have more information about the F-35 than we've had about three years ago in terms of its capability, in terms of its reliability and maintainability," Bogdan said. "In terms of its cost, in terms of [operations and sustainment] O&S, in terms of its cost of procurement. And they've all come down. So we've got a lot of hard facts to back up what we can show the Canadians in terms of what their value of the F-35 is."

Valerie Insinna contributed to this report.

Twiter: @AaronMehta