Defence Minister Rob Nicholson rises in the House of Commons during question period in Ottawa on Monday, Oct. 6, 2014.

Image Credit: THE CANADIAN PRESS/Justin Tang

OTTAWA - A divided House of Commons prepared to vote Tuesday to send Canadians back to war with the Conservatives insisting it is Canada's duty and opposition parties warning of a potential major mistake.

The Conservatives used the waning hours of debate to focus on Canada's responsibility to act against the brutality of the Islamic State of Iraq and the Levant, a vicious offshoot of al-Qaida currently in control of swaths of Iraq and Syria.

But the New Democrats and Liberals are concerned they don't have enough information about how far the Conservatives are willing to go.

Six CF-18 fighter-bombers, two CP-140 surveillance planes, one aerial tanker aircraft and 600 personnel have been tapped to join coalition air strikes in Iraq for up to six months, but there will be no troops directly involved in ground combat, says the motion before the Commons.

"We know that when we face this kind of a threat, a terrorist caliphate established in the open that threatens this country and threatens it quite explicitly and directly, that is not something we can just sit back and watch," Prime Minister Stephen Harper said during question period.

Video surfaced last month of presumed ISIL fighters making direct threats against Canadians and those videos were invoked several times by the Tories over the course of debate.

They also repeatedly mentioned ISIL atrocities, including the beheading of journalists and aid workers, sexual violence and the persecution of religious minorities.

While acknowledging the brutality, the opposition parties said there is no proof air strikes will work.

"Doesn't the prime minister realize that these current tactics, the same ones he wants to follow, will only create more recruits for (ISIL) and can in fact be disastrously counterproductive?" asked NDP Leader Tom Mulcair, citing reports that thousands of people have enlisted with ISIL since the airstrikes began.

The NDP have proposed an amendment to overhaul the motion entirely and switch the focus to supplying arms to local fighters battling ISIL and increasing humanitarian support.

The Liberals argued that Canada's military contribution has not been thoroughly considered.

"The fact of the matter in terms of our commitment financially and with equipment and human resources if you commit in one area, it is conceivable that there is less you can commit in the other areas," said Liberal MP Wayne Easter.

"And so strategically we do not know the whole picture and the prime minister has failed to outline that."

There is no requirement for the House of Commons to approve combat missions, but the prime minister promised this mission would be put up for debate when he first floated the idea of a new military role in Iraq.

Canada initially stayed out of the international combat campaign against ISIL, which began with U.S. strikes in August.

At the close of a NATO meeting in September, Canada announced a commitment of up to 69 special forces soldiers to advise Iraqi and Kurdish fighters for 30 days. That mission is to be extended with the passage of the motion.

Harper signalled at the time that more might be done and in September he disclosed during an interview in New York that Canada was weighing a combat role.

A motion laying out the plan was introduced in the Commons on Friday and Harper laid out the specifics.

In addition to calling for air strikes in Iraq, he left the door open to a campaign in Syria as well, if called for by the Syrian government.

The Americans are currently bombing ISIL positions in Syria as militants threaten towns on the Turkish border.

Debate on the motion began Monday and the Conservatives limited its length so the vote could take place Tuesday.

On Monday, the Conservatives also announced an increase in humanitarian aid, promising up to $10 million for victims of sexual violence.

The Foreign Affairs Department says that since the beginning of 2014, more than $28 million has been allocated to humanitarian needs in Iraq.

WITH CF-18s POISED FOR TAKEOFF, IRAQ DEBATE LEAVES CANADIANS IN A FOG OF WAR

Murray Brewster

OTTAWA - Canadian CF-18s will soon be heading off to war in Iraq, leaving Parliament and the public in a fog about some key elements of the military commitment notably what efforts will be made to limit civilian casualties.

The House of Commons stands poised to approve a motion, likely on Tuesday, that would deploy six fighter-bombers, two CP-140 surveillance planes and one refuelling aircraft for coalition air strikes in Iraq for up to six months.

Tuesday's vote comes as the Pentagon warns that extremists with the Islamic State of Iraq and the Levant have "gotten better at concealment" since the U.S., Britain, France and key Arab countries began air raids.

U.S. Rear Admiral John Kirby, the assistant secretary of defence for public affairs, told reporters in Washington that extremists who rode around in the open have now dispersed and are hiding among the civilian population, forcing allied air forces to change their own strategy.

"We've seen them change some of their tactics," Kirby said.

"Before the airstrikes happened, they were they pretty much had free rein. They don't have that free rein anymore, because they know we're watching from the air."

The Harper government was mute during Monday's debate about what precautions would be taken to prevent bombs from going astray and killing innocent people.

Defence Minister Rob Nicholson would only say that the air force will "live up to the highest standards."

National Defence was asked what sort of legal agreements were in place to protect Canadian pilots from possible accusations of targeting civilians.

A spokeswoman for Nicholson, Johanna Quinney, would only respond with the blanket assurance that the air force is "authorized to strike ISIL in the Republic of Iraq."

NDP Leader Tom Mulcair said the "Conservatives have gone out of their way to stifle informed debate."

The use of airstrikes and the resulting civilian casualties was a big factor in turning many Afghans against NATO forces in that country. The anger became so strong that the U.S. general leading the war effort was forced to place limits on how and when they could be used.

The Libya bombing campaign was conducted with relatively few civilian casualties, but those deaths were reviewed by a United Nations commission that urged the military alliance to conduct its own further investigation.

Green party Leader Elizabeth May questioned the effectiveness of airstrikes, citing published reports from the region quoting Kurdish fighters who say the airstrikes have failed to slow ISIL's advance.

"They scattered and re-form after the jets leave," said May, who asked for evidence that the bombing runs would prove effective.

She wondered whether "the planned mission will do anything other than to fall into the trap (ISIL) has set to get us involved for their propaganda and ongoing efforts to destabilize the region and encourage recruitment."

Neither Nicholson nor National Defence would say which of Canada's principal fighter bases Bagotville, Que., or Cold Lake, Alta. would contribute the CF-18s.

The Conservative government also refused to say where the aircraft would be based in the Middle East. Britain, on the other hand, has made no secret of the fact its Tornado GR4 fighter jets are operating out of Cyprus.

Nicholson would not provide an estimate on what the deployment could cost, despite the fact the U.S. openly acknowledged last week its campaign is already closing in on the $1-billion mark.

In the case of Canada's nearly eight-month long air assault on Libya in 2011, which used a force of identical size, the incremental cost the amount of money spent over and above what normal expenditures would have been without the mission was roughly $103.6-million.

Also left unanswered by the debate was the question of under what circumstances Canadian aircraft would conduct missions over Syria.

Last week, Prime Minister Stephen Harper said such raids would only be done with the consent of the Syrian government, but the NDP expressed outrage at the notion.

President Bashar al-Assad's government, which ISIL has been fighting, would stand to benefit. Conservative ministers have so far not explained how such consent for Canadian bombing would be obtained.

Liberal foreign affairs critic Marc Garneau said the government failed to make the case for war.

"The prime minister is taking us across the Rubicon by deciding on a combat mission," he said. "Once a country makes that decision, there is no turning back the clock."

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Note to readers: This is a corrected story. A version of this story that moved Oct. 6 said the cost of Canada's bombing campaign in Libya in 2011 was $350 million.

News from © The Canadian Press, 2014