OTTAWA -- National Defence laid out its timeline Monday for replacing Canada's aging fleet of jet fighters, saying a contract won't be finalized until at least 2018.

But the Harper government was quick to say details in its long-anticipated defence acquisition guide should not be treated as gospel.

The document, which is meant to provide industry a snapshot of the military's expected equipment needs over the next two decades, contains some 200 different pieces of kit, a schedule of when the government is expected to buy and roughly how much the programs are worth.

The guide says the replacement program for the CF-18s will remain in the definition phase between 2015 and 2017, meaning a decision could be pushed out past the next federal election, slated to take place in less than 18 months.

More importantly, it says there will be a request for proposals between 2017 and 2019.

It goes on to say the awarding of the contract is expected between 2018 and 2020, which is around the time when many of the CF-18s are expected to reach the end of their service life.

The guide also proposes upgrades to the CF-18 electronic warfare suites, as well as software and training improvements for the fighters, originally purchased in the 1980s.

What that means for the fate of the controversial F-35 program is unclear.

The federal cabinet is examining a series of reports, including an independent panel's market analysis of which fighter aircraft could meet the future needs of the air force.

It could decide over the next few weeks to continue with the stealth fighter plan or throw the replacement program open to a full-blown competition.

Another option might be for cabinet to ask the air force to rewrite its statement of requirements.

The federal Liberals are taking the guide as a sign that there will be a competition. Defence critic Joyce Murray called on the Conservatives to guarantee that the Prime Minister's Office will allow open bidding, and not overrule the plan.

"Great news today from the Department of National Defence," Murray told the House of Commons during question period.

But Public Works Minister Diane Finley, whose department is overseeing the troubled program, warned against reading too much into the timeline, saying no decision has been made and likely won't be any time soon.

"We've had an independent panel of outside experts review the assessment that was done by the RCAF," Finley said.

"Over the next several weeks we are going to be carefully reviewing a number of reports on this subject, so that we can make sure that we get the proper equipment our men and women in uniform need to do their job."

Johanna Quinney, a spokeswoman for Defence Minister Rob Nicholson, was even more specific, saying the government reserves the right to change its mind.

"The majority of the projects in this publication do not have formal authority from the government and remain subject to change in terms of scope, cost and schedule including termination without any further explanation or liability," Quinney said in an email.

It's not the first time the 2018 date has been floated in relation to the fighter replacement.

Earlier this year, the manufacturer of the F-35 indicated that the Harper government had pushed its potential delivery date for the first aircraft off until that year, holding its place in the line of countries that have already agreed to buy the jet.

But Steve O'Bryan, vice-president of business development at Lockheed Martin, said in order to meet the timeline, Canada would have to make a decision and begin making payments next year.

The federal government has not signed a delivery contract, but the partnership arrangement among nations requires them to put begin putting money down three years before the first plane arrives.

The guide also says the government's plan to buy surveillance and combat drones, originally conceived in 2007, will be put off until 2020.

The military plans to extend the life of its C-150 Polaris transports and tankers out beyond 2026 and will modernize its troubled submarine fleet so it can remain active well into the 2030s.