President Donald Trump has announced the concept he wants for his future Golden Dome missile defense program — a multilayered, $175 billion system that for the first time will put U.S. weapons in space.

Speaking Tuesday from the Oval Office, Trump said he expects the system will be “fully operational before the end of my term," which ends in 2029, and have the capability of intercepting missiles “even if they are launched from space.”

It's likelier that the complex system may have some initial capability by that point, a U.S. official familiar with the program said.

Trump, seated next to a poster showing the continental U.S. painted gold and with artistic depictions of missile interceptions, also announced that Gen. Michael Guetlein, who currently serves as the vice chief of space operations, will be responsible for overseeing Golden Dome's progress.

Golden Dome is envisioned to include ground- and space-based capabilities that are able to detect and stop missiles at all four major stages of a potential attack: detecting and destroying them before a launch, intercepting them in their earliest stage of flight, stopping them midcourse in the air, or halting them in the final minutes as they descend toward a target.

For the last several months, Pentagon planners have been developing options — which the U.S. official described as medium, high and “extra high” choices, based on their cost — that include space-based interceptors. The official spoke on condition of anonymity to detail plans that have not been made public.

The difference in the three versions is largely based on how many satellites and sensors — and for the first time, space-based interceptors — would be purchased.

The Congressional Budget Office estimated this month that just the space-based components of the Golden Dome could cost as much as $542 billion over the next 20 years. Trump has requested an initial $25 billion for the program in his proposed tax break bill now moving through Congress.

The Pentagon has warned for years that the newest missiles developed by China and Russia are so advanced that updated countermeasures are necessary. Golden Dome's added satellites and interceptors — where the bulk of the program's cost is — would be focused on stopping those advanced missiles early on or in the middle of their flight.

The space-based weapons envisioned for Golden Dome “represent new and emerging requirements for missions that have never before been accomplished by military space organizations,” Gen. Chance Saltzman, head of the U.S. Space Force, told lawmakers at a hearing Tuesday.

China and Russia have put offensive weapons in space, such as satellites with abilities to disable critical U.S. satellites, which can make the U.S. vulnerable to attack.

Last year, the U.S. said Russia was developing a space-based nuclear weapon that could loiter in space for long durations, then release a burst that would take out satellites around it.

Trump said Tuesday that he had not yet spoken to Russian President Vladimir Putin about the Golden Dome program, “but at the right time, we will,” he told reporters at the White House.

There is no money for the project yet, and Golden Dome overall is “still in the conceptual stage,” newly confirmed Air Force Secretary Troy Meink told senators during a hearing Tuesday.

While the president picked the concept he wanted, the Pentagon is still developing the requirements that Golden Dome will need to meet — which is not the way new systems are normally developed.

The Pentagon and U.S. Northern Command are still drafting what is known as an initial capabilities document, the U.S. official said. That is how Northern Command, which is responsible for homeland defense, identifies what it will need the system to do.

The U.S. already has many missile defense capabilities, such as the Patriot missile batteries that the U.S. has provided to Ukraine to defend against incoming missiles as well as an array of satellites in orbit to detect missile launches. Some of those existing systems will be incorporated into Golden Dome.

Trump directed the Pentagon to pursue the space-based interceptors in an executive order during the first week of his presidency.

Canada wants to join Golden Dome missile-defence program, Trump says

Donald Trump says Canada has asked to join the missile-defence program his administration is building, adding a new chapter to a long-running cross-border saga.

The U.S. president dropped that news in the Oval Office on Tuesday as he unveiled the initial plans for a three-year, $175 billion US project to build a multi-purpose missile shield he's calling the Golden Dome.

"Canada has called us and they want to be a part of it," Trump said. "They want to hook in and they want to be a part of it."

Canada will pay its "fair share," he added. "We'll work with them on pricing."

Ottawa confirmed it's talking to the U.S. about this but added a caveat. In a statement, the federal government cast missile-defence discussions as unresolved and as part of the overall trade and security negotiations Prime Minister Mark Carney is having with Trump.

What this means is still extremely murky. It's unclear what, exactly, Canada would contribute; what its responsibilities would include; what it would pay; and how different this arrangement would be from what Canada already does under the Canada-U.S. NORAD system.

Refused to join

Canada has long participated in tracking North American skies through NORAD, and feeds that data into the U.S. missile-defence program.

But Canada never officially joined the U.S. missile program, which was a source of controversy in Ottawa in the early 2000s when Prime Minister Paul Martin's government refused to join.

That previous refusal means Canadians can monitor the skies but not participate in any decision about when to launch a hypothetical strike against incoming objects.

New developments have forced the long-dormant issue back onto the agenda.

For starters, the U.S. is creating a new system to track various types of missiles — one more sophisticated and multi-layered than Israel's Iron Dome, intended to detect intercontinental, hypersonic and shorter-range cruise weapons.

And this happens to be occurring as Canada's sensors in the Arctic are aging out of use. Canada has committed to refurbishing those sensors.

Rumblings of Canada's interest started months ago

The first public indication that these combined factors were fuelling a policy shift in Canada came in public comments made earlier this year in Washington.

One U.S. senator said, in February, that he'd heard interest in the missile program from a Canadian colleague, then-defence minister Bill Blair.

Blair publicly acknowledged the interest, saying that, given the upgrades being planned by both the U.S. and Canada, the partnership "makes sense."

But the form of Canadian participation is, again, unclear. The U.S. commander for NORAD appeared recently to suggest that Canada's participation will be limited to tracking threats.

One missile-defence analyst says it sounds like an extension of existing Canada-U.S. co-operation through NORAD. Still, says Wes Rumbaugh, it's interesting that Trump chose to draw attention to it. Trump mentioned Canada's role several times, unprompted, during his announcement Tuesday.

As for the president's three-year timeframe, Rumbaugh calls it a long shot. He predicts that only part of the system could be built in that period, and that it will take more years, and more funding, to complete.

It could take much, much more funding. The Congressional Budget Office estimates this project could cost hundreds of billions more than the $175 billion US figure cited by the president.

"This is still a significant challenge," said Rumbaugh, a fellow in the missile defence project at the Center for Strategic and International Studies think-tank in Washington.

"We're talking about sort of a next-generation and a widely enhanced missile-defence system. We're talking about a step-change evolution in American air and missile defence systems that will require significant investment over potentially a long time period."

Canada confirms Golden Dome discussions

Nearly three hours after Trump's announcement, Ottawa confirmed the discussions are happening. An evening statement from Carney's office said Canadians gave the prime minister an electoral mandate to negotiate a comprehensive new security and economic relationship with the U.S.

"To that end, the prime minister and his ministers are having wide-ranging and constructive discussions with their American counterparts," said the statement.

"These discussions naturally include strengthening NORAD and related initiatives such as the Golden Dome."

A Canadian cabinet minister involved in similar discussions in the early 2000s says it's high time the conversation resumed.

"I see this as a positive," said David Pratt, a Liberal defence minister in the first Martin cabinet.

He favoured Canada's participation in a North American missile defence system back then but says the government blanched out of fear of political blowback, with its minority government fragile.

He said the refusal to join came with a cost. In part, NORAD lost part of its potential vocation, as missile interception became a U.S.-only activity, and related research and manufacturing opportunities flowed to the U.S., he said.

The specific U.S. ask of Canada was never fully defined back then, he said. Pratt recalls negotiations having just gotten underway about what role Canada would play and whether it would merely host sensors or also interceptors on its soil.

"I'm hoping we'll see NORAD assume what should have been its rightful role," he told CBC News.

What is the 'Golden Dome'? Space missile defense system explained

 President Donald Trump and Defense Secretary Pete Hegseth announced plans for the Golden Dome missile defense system on Tuesday.

Speaking in the Oval Office, Trump said he expects the system will be "fully operational before the end of my term," which ends in 2029, and have the capability of intercepting missiles "even if they are launched from space."

Trump also announced that Gen. Michael Guetlein, who currently serves as the vice chief of space operations, will be responsible for overseeing Golden Dome's progress.

What is the Golden Dome?

Dig deeper

Golden Dome is envisioned to include ground and space-based capabilities that are able to detect and stop missiles at all four major stages of a potential attack.

This includes detecting and destroying them before a launch, intercepting them in their earliest stage of flight, stopping them midcourse in the air, or halting them in the final minutes as they descend toward a target.

The plan is to build and launch 400 to up to more than 1,000 satellites to track the movement of missiles around the globe, sources told Reuters.

A fleet of 200 attack satellites armed with missiles or lasers would then eliminate any enemy projectiles.

How much will it cost?

For the last several months, Pentagon planners have been developing options — which a U.S. official described as medium, high and "extra high" choices, based on their cost — that include space-based interceptors.

By the numbers

On Tuesday, Trump announced the concept he wants for the future Golden Dome program is a multilayered $175 billion system that will for the first time put U.S. weapons in space.

The Congressional Budget Office estimated this month that just the space-based components of the Golden Dome could cost as much as $542 billion over the next 20 years.

Who will build it?

The backstory

Last month, sources told Reuters that the two frontrunners to build this massive project were Elon Musk’s SpaceX and another unnamed candidate.

SpaceX is teaming up with software maker Palantir and defense technology company Anduril for a joint bid, with all three of the companies having met with top officials in the Trump administration and the Pentagon to pitch their proposal, sources told Reuters at the time.

SpaceX is not anticipated to play a role in the weaponization of the satellites in this project, however.

The Pentagon has received interest from more than 180 companies to help build the project, a U.S. official told Reuters.