In his first major speech on the future of Canada's role in Iraq, Liberal Leader Justin Trudeau left the door open for his party to back an expansion of the 30-day non-combat mission that is set to wrap up on Friday.

But he made it clear that he hasn't been won over by Prime Minister Stephen Harper's rhetoric on "the nobility of combat."

In a mid-morning speech to a mostly left-of-centre crowd attending an annual policy conference organized by Canada 2020, Trudeau pointed out that, as yet, Canadians "don't know exactly what he has offered the Americans."

Canadians 'anxious': Trudeau

"We don’t know what our role will look like. We don’t know how long our contribution is expected to last. We don’t know how helpful our CF-18s will truly be," he added.

All those unanswered questions, he said, "makes Canadians understandably anxious."

Liberal Leader Justin Trudeau spoke at news conference following his keynote address to a Canada2020 event in Ottawa Thursday. (Sean Kilpatrick/The Canadian Press) "Mr. Harper is intent on taking Canada to war in Iraq,"Trudeau stressed. "He hasn't made the case for it. He hasn’t even tried."

The prime minister, Trudeau said, "would have you believe that Canada’s best contribution to this effort is a handful of aging war planes," but he believes that there could be "significant, substantial, non-combat roles" for Canada in everything from humanitarian aid to political reform.

"This is something we do well."

During a post-speech chat on stage with Canada 2020 president Don Newman, Trudeau noted that there are "hundreds of thousands" of displaced people in the region who don't want to leave because "that's where their homes are."

"They need support to get through this very, very difficult time, and Canada has a capacity and expertise in doing just that," he pointed out.

'Whip out our CF-18s'

"Why aren't we talking more about the kind of humanitarian aid that Canada can and must be engaged in, rather than, you know, trying to whip out our CF-18s and show them how big they are? It just doesn't work like that in Canada."

A spokesman for the Prime Minister's Office called Trudeau's comments "disrespectful," and suggested the Liberal leader had "made light of a serious issue."

"Our involvement in the fight against ISIL is, and has been, motivated by a desire to do our part in fighting a group that has made direct terrorist threats against Canada and Canadians, in addition to carrying out atrocities against children, women, and men in the region," Jason MacDonald said in a written statement provided to CBC News.

"As the Prime Minister has said: we take that seriously and will do our part."

He also took issue with Trudeau's suggestion that Canada wasn't doing enough on the humanitarian side.

"Canada is making a significant contribution to the humanitarian effort as well. In fact, our contributions to date would rank us as one of the top donors in Iraq," he said.

That disapproval was echoed by Employment Minister Jason Kenney, who spoke at the same conference later in the day.

He told reporters that he was "disturbed" to hear the Liberal leader "crack wise" with a "juvenile high school joke" while discussing "genocide."

Earlier, Kenney took his criticism to Twitter, where he posted a link to the CBC video of Trudeau's comments.

"Is this how Prime Minister Justin Trudeau would conduct himself in discussing use of air power at a NATO summit?" he wondered.

Onus on Harper for support, Trudeau says

Under questioning from reporters following the speech, Trudeau stuck to his contention that the onus is on Harper to sell parliamentarians — and Canadians — on any proposal to expand Canada's role beyond the advisers already on the ground.

Asked what the optics would be of Canadian troops heading overseas without at least one opposition party voting to support the mission in the House, Trudeau indicated that he saw that as the prime minister's concern.

"This should be beyond partisanship."

MPs could be asked to vote on an expansion of the current mission as early as next Monday.

The government is expected to provide more details on the next phase of Canada's participation, which will likely include taking part in the airstrikes already underway.

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