Canadian troops will stay in Iraq for the next two years and expand their "advise and assist" role by training other local security forces, the Liberal government announced Thursday.

To this point, the roughly 200 Canadian special forces trainers in Iraq have concentrated their attention on teaching Kurdish Peshmerga fighters the finer points of combat.

But Defence Minister Harjit Sajjan and Foreign Affairs Minister Chrystia Freeland said in a statement the extension to March 31, 2019, will allow the training of "new potential partners within the Iraqi security forces."

The military is also adding a C-130J Hercules transport plane to the mission list, presumably to move troops and equipment around the country.

The former Conservative government was very deliberate when it chose in 2014 to link Canada's training in Iraq with the Kurds, who occupy a semi-autonomous region in the north.

The U.S. led the rebuilding of Iraqi security forces, which were riven by sectarian strife and melted away in the face of the ferocious advance by smaller ISIS forces three years ago.

The Iraqis have been accused of battlefield human rights abuse more often than the Kurds, and experts note that some units are more loyal to the central government in Baghdad than others.

Sajjan, speaking to reporters via a conference call from NATO headquarters in Brussels, acknowledged it is a consideration.

"We're going to be working with our coalition partners to make sure we work with credible Iraqi security forces, and human rights will always be a focus for us," he said.

University of Ottawa defence expert Thomas Juneau said the Canadians will also have to be careful in selecting who they train for political reasons.

"Working with Iraqi forces will be problematic," he said. "The Iraqi military and security forces are heavily fragmented. Some units follow or are more loyal to specific factions within the Iraqi government."

The Kurds have a long-standing request for Canadian trainers to instruct them in counter-insurgency warfare, which is what they expect to face once the conventional battle for Mosul, Iraq's second-largest city, ends some time in the next few months.

A Canadian special forces soldier, left, speaks with Peshmerga Capt. Omar Mohammed Dhyab, second left, and other fighters at an observation post in February in northern Iraq. (Ryan Remiorz/Canadian Press)

The training Canadian special forces have provided to the Kurds thus far involves traditional combat skills, not the intelligence-driven shadow warfare that characterized the decade-long combat commitment in Afghanistan.

Most military planners, including many at the Pentagon, expect ISIS to revert to a guerrilla war once it has been driven out of Mosul.

Most the U.S. training of Iraqi forces has taken place in bases in southern and central parts of the war-torn country. The decision on Thursday means Canadians could expand their presence beyond the north enclave where they have operated for the last three years, said Sajjan.

Precisely who and what kind of training will take place in this new phase of the mission was not made clear in the government press release on Thursday.

Sajjan said those details are going to be worked out by the country's chief of the defence staff.

Debate over combat vs. non-combat role

The extension comes as debate continues over whether Canada is actually involved in active combat in northern Iraq, after a Canadian special forces sniper shot an ISIS fighter from a record 3,540 metres, the longest confirmed kill shot in military history.

On Thursday, the country's top military commander, Gen. Jonathan Vance, said he is "extremely proud" of the military's accomplishments in the region.

"I am confident these additional authorities will help us be more agile and flexible as we respond to the needs of our allies and partners," he said, also in a statement.

Iraqi security forces and Kurdish Peshmerga fighters have been deeply involved in the battle to retake Mosul from deeply entrenched ISIS fighters.

On Thursday, the Iraqi government declared the liberation of Mosul was "imminent."

Canadian and allied special forces soldiers have provided not only advice, but covering fire — something that prompted fresh political debate in Canada about whether the country is involved in a combat mission.

NDP Leader Tom Mulcair has been getting increasingly vocal.

"I want Mr. Trudeau to come and make his case to the elected officials in Parliament, the way Mr. Harper did," Mulcair said Thursday. He was referring to debates in the House of Commons, sponsored by the previous Conservative government, on earlier military deployments.

"Are we training Iraqis in addition to the Kurdish forces that we were training before? If so, what does that mean? Are we operating more than one base? If so, tell us what the dangers are."

Sajjan insisted the Liberal government has already discussed the mission in Parliament and Thursday's announcement represented a refinement of the existing strategy.

No return to Afghanistan: Trudeau

Also Thursday, NATO announced it wants to boost its presence in Afghanistan, calling on allied nations to contribute troops to both its train-and-assist mission for Afghan forces and counterterrorism operations against the Taliban, al-Qaeda and ISIS militants.

But in Charlottetown Thursday, Prime Minister Justin Trudeau ruled out Canadian troops returning to Afghanistan, saying "Canada is looking to be helpful in other places."

"There are absolutely no plans to send any troops back to Afghanistan. We have served there with distinction, with valour, over 10 years and made a significant impact," he told reporters.