Canadian Prime Minister Mark Carney on Tuesday announced a radar purchase from Australia and an expansion of military operations in the Arctic while visiting Canada’s far north in an effort to assert sovereignty over the increasingly contested region.

The prime minister’s office said the Canadian $6 billion ($4.2 billion) Over-the-Horizon Radar system will provide early warning radar coverage from the Canada-United States border into the Arctic.

Carney announced the purchase at a military base in the capital of the Inuit-governed territory of Nunavut on his last stop after visiting Paris and London for meetings with leaders there.

The Australian radar system will consist of a series of pillars almost a mile (1.6 kilometers) in length. Officials said that the system would have a smaller footprint than what the similar American system would take up.