Foreign Minister Pierre Pettigrew (search) said Thursday that Canada will opt out of the contentious U.S. missile defense scheme, a move expected to further strain relations with the United States and please constituents at home.

Pettigrew, putting an end to nearly two years of debate over whether Canada should sign on to the multibillion-dollar program, said Ottawa would remain a close ally of Washington in the fight against global terrorism and continental security.

When President Bush visited Canada in December, he surprised Ottawa with several unsolicited pitches for support of the defense shield, which has been testing interceptors capable of taking out incoming missiles targeted at the North American continent.

However, polls indicate that most Canadians are opposed to the scheme. Many believe that the umbrella, when fully implemented, could lead to an international arms race.

Prime Minister Paul Martin (search), who leads a tenuous minority government, has said that Ottawa would not support what he called the "weaponization of space."