OTTAWA - The Conservative government insists all of its new F-35 jets will arrive with the hardware needed to talk to ground troops and prevent friendly fire, but some will still need upgrades to make it work.

Associate Defence Minister Julian Fantino said the stealth jets will be ready to do whatever the government asks, when it asks.

"All of Canada's F-35s will not only be capable of operating overseas the moment we get them, but be able to communicate with aircraft and know where friendly ground units are well in advance of deployment on operations," Fantino said under questioning in the House of Commons.

While the multi-role fighter will have the hardware and be wired to track ground troops, the actual feature that powers the system is not scheduled to be installed until a major upgrade in 2019, according to U.S. military technical journals -- something also alluded to in heavily censored Canadian air force documents, obtained under access to information laws.

Asked to reconcile the conflicting information, a spokesman for Fantino said in an email response that the air force would have to load the feature into the first handful of jets.

Chris McCluskey says each aircraft comes equipped with a Blue Force Tracker "capability" when it arrives in Canada, "with the exception of a small number of aircraft in which it is scheduled for installation before deployment on missions."

The technical journals and documents also discuss the expected absence of a transmission system, known as a Link 16.

McCluskey denied the F-35 will be without that capability, which allows pilots to send short text messages and data to ships, older aircraft and ground stations.

While the stealth fighter will have the hardware and antenna for the Link 16, U.S. technical journals say there is a furious debate taking place among air force planners and designers about its limitations and whether it could compromise the radar-evading capability of the F-35 by giving away its position.

They also question whether the system, which is standard on existing warplanes, can handle all of the high-resolution video and data the new jet is capable of pumping out.

"Link 16 can't carry the kind of data the F-35 can gather," said the online publication Live Science, one of several U.S. journals tracking the development of the aircraft.

Engineers equate the situation to difference between using dial-up and broadband Internet and wonder whether a newer transmission system -- called a Multifunction Advanced Data-Link -- will meet the needs.

The multifunctional system only communicates with other so-called 5th generation -- or stealth jets -- such as the F-22 Raptor or the B-2 bomber.

Both Lockheed Martin, the manufacturer, and the Pentagon office overseeing the F-35 project didn't respond to requests to comment.

Opposition critics hammered the government over the planned purchase, which could run taxpayers between $16 billion and $30 billion depending upon the estimate.

New Democrat MP Christine Moore accused the government of not knowing what it was doing on the file.

"We have communications and sustainability problems with the F-35," she said during question period and demanded the project be put to open tender.

The auditor general pointed out on Tuesday that the Defence Department is not sure it has set aside enough cash in future budgets to repair and maintain the new equipment being purchased for the military by the Harper government.

Although John Wiersema's report did not single out F-35 sustainment, the Parliamentary Budget Officer did focus some of his criticism last spring on the estimated cost of maintenance, which he accused the Conservatives of low-balling.