Prime Minister Stephen Harper accused his Liberal and NDP counterparts of playing politics by opposing the Canadian combat mission against Islamic State militants in Iraq and Syria.

"I think on behalf of both Justin Trudeau and Thomas Mulcair, their positions on the military mission in Iraq and Syria, the mission against ISIS, is irresponsible electoral politics, and I think most Canadians understand that," Mr. Harper said at a news conference in Quebec City on Thursday.

The Prime Minister focused his attack on Mr. Trudeau, who recently reiterated his plans to put an end to the CF-18 bombing mission against IS positions in Iraq and Syria, and called for the restoration of diplomatic relations with Iran.

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"It's very strange … to say his priority is the restoration, or to become best friends, with one of the state sponsors of terrorism in the world, the government of Iran, and that he wants to cut the relationship that we have established with all of our allies and with a large international coalition to take the fight against the so-called Islamic State in Iraq and Syria," the Conservative Leader said.

Mr. Harper added IS "has executed and is planning attacks against Canada and Canadians."

Canada has six CF-18s bombing Islamic State targets in Iraq and Syria and two surveillance planes monitoring the battle from the air as well as one air refuelling plane. About 600 personnel are supporting this work from Kuwait.

The military also has nearly 70 special forces soldiers training peshmerga fighters in their battle against Islamic State forces.

"We'd move away from the CF-18 [bombing] mission," Mr. Trudeau said in an interview on CBC's Power & Politics this week. "This government has failed miserably to demonstrate why the best mission for Canada is to participate in a bombing mission."

Under a Liberal government, Mr. Trudeau said a priority for the Canadian Forces would be "training up local troops doing the fighting on the ground."

The fate of Canada's military mission in Iraq and Syria will be a major issue in the next election campaign, with the NDP and the Liberal Party having voted against the deployment supported by the Conservative government.

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Mr. Harper was in Quebec City to announce $7-million in federal funding for a tall ships regatta that will make stops in the Maritime provinces and Quebec during the celebrations of Canada's 150th anniversary in 2017.