President George W. Bush is planning soon to meet Canada's Prime Minister Paul Martin, the White House said on Tuesday, despite unease over Martin's decision not to take part in the U.S. missile-defense system. A three-way meeting between Bush, Martin and Mexican President Vicente Fox is being planned. White House spokesman Scott McClellan said details of the meeting were still being completed. Canada's minority Liberal government made an abrupt change in policy and said last Thursday it would not take part in the planned missile defense system, which is unpopular with many Canadian voters. The system is designed to shoot down ballistic missiles from adversaries such as North Korea, but the program has been marred by test failures and it failed to meet Bush's goal of being operational by the end of 2004. Martin came to power in 2003 saying he supported signing on to the missile shield and deepening the integration of the two countries' defenses. "Canada did inform us about their decision and we're going to continue to work with Canada and cooperate with them on shared defense priorities. We've had good cooperation on defense issues in the past. We will in the future," McClellan said.