Canadian Prime Minister Mark Carney announced on Wednesday that his government is in discussions with the U.S. regarding participation in President Donald Trump’s upcoming Golden Dome missile defense initiative.

The multilayered, $175 billion system would for the first time put U.S. weapons in space. Trump said the previous day he expected the system to be fully operational by the end of his term in 2029.

“Is it a good idea for Canada? Yes, it is a good to have protections in place for Canadians,” Carney said.

Carney confirmed he’s had talks with Trump about it and said there are discussions with senior officials. Trump said the Canadian government had contacted his administration indicating it wants to join the program and that he will work with Ottawa to ensure it contributes its “fair share.”

Golden Dome is envisioned to include ground- and space-based capabilities 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.

“It’s something that we are looking at and something that has been discussed at a high level.” Carney said. “But not I’m not sure one negotiates on this. These are military decisions that have been taken in that context, and we will evaluate it accordingly.”

Carney warned that Canada faces potential missiles threats in the “not-too-distant future” that could come from space.

“Is Canada going to be doing this alone or with the United States? Because with a Golden Dome, there will be discussions that could have an impact on Canada, but Canada wouldn’t be a part of them,” Carney said.

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.

Canada and the U.S. are partners in the North American Aerospace Defense Command, the combined organization that provides shared defense of airspace over the two nations.

The newly elected Carney spent much spent much of the last few months saying the old relationship with the U.S. based on steadily increasing integration is over. Trump has infuriated Canadians by saying Canada should be the 51st state.

“We cooperate if necessary but not necessarily cooperate,” Carney said.