Canadian Prime Minister Mark Carney says his government is talking to the U.S. about joining President Donald Trump’s future Golden Dome missile defense program.

President Donald Trump picked a design for his Golden Dome missile defense system and named a leader of the ambitious $175 billion defense program. The program, first ordered by Trump in January, aims to create a network of satellites, perhaps numbering in the hundreds, to detect, track and potentially intercept incoming missiles.

The project has been a priority for President Trump since he took office, having promised during the campaign to build a defense system against foreign threats similar to Israel’s Iron Dome.