Canada announced Thursday it will enter formal talks with the United States about joining a proposed missile defense system (search) but only if the program meets the Canadian national interest.

Speaking in Parliament, Defense Minister John McCallum (search) said Canada would benefit from being part of discussions on a system intended to secure North America.

"Let me be clear. While we believe missile defense has the potential to benefit Canada, our participation is not unconditional," he said, adding the government would not agree to any space-based defense system.

Nevertheless, McCallum said entering talks was in Canada's interest.

"A sovereign government has a duty and a responsibility to do its own due diligence to ensure maximum protection of the lives of its citizens," he said.

Prime Minister Jean Chretien (search) and McCallum confirmed earlier this month that the government was considering joining the defense shield, signaling a change in its previous skepticism about what is known as the Star Wars issue due to concerns that ballistic missile defenses might spark an arms race.

U.S. officials have criticized Canada for cutting defense spending too much in budget-balancing during the 1990s and called for Chretien's government to play a larger role in North American defense.

In Washington, U.S. State Department (search) spokesman Richard Boucher called missile defense "very important for us and for North America."

The Canadian announcement shows the two countries "still have many interests in common, including a defense of the people," Boucher said.