Canada will invest C$4.9 billion (US$3.8 billion) over the next six years to modernise Norad, the joint US-Canadian North American defence organisation that experts say is in dire need of upgrades, defence minister Anita Anand said on Monday.

The more-than six-decade-old system detects security threats to North America, and its early warning radar system for the polar region dates back to the late 1980s.

Anand, speaking at an air base in Trenton, cited Russia's invasion of Ukraine in February as one of the reasons the investments are finally coming now.

"The threat environment has changed," Anand said. "This is the most significant upgrade to Norad from a Canadian perspective in almost four decades," Anand said, adding that the investment plan has a total value of about C$40 billion over the next 20 years.

The minister also said new technologies are needed because "autocratic regimes" now have hypersonic weapons and advanced cruise missiles.

Canada's arctic region represents about 40 percent of its total landmass, though it is sparsely populated and has little infrastructure. Much of Russia's Arctic area, which is about a fifth of its landmass, faces Canada and Alaska.

Anand said this C$4.9 billion investment is new money, and adds to the C$8 billion in extra defence spending Canada promised in its 2022 budget.

The new money will focus on areas such as upgrades to surveillance systems, new defensive weapons and research.

It will include an over-the-horizon radar system to provide early warning coverage and threat tracking, and new air-to-air missiles to engage threats from short-, medium-, and long-ranges. (Reuters)