OTTAWA -- The record-breaking kill shot by a Canadian sniper in Iraq should be "celebrated," Prime Minister Justin Trudeau said Tuesday, even as he insisted Canada's mission in the battle-racked country remains a non-combat one.

"What happened there is, first of all, something to be celebrated for the excellence of the Canadian Forces in their training, in the performance of their duties," Trudeau told a news conference.

"But it's also something to be understood as being entirely consistent with what Canada is expected -- and Canadians expect our forces -- to be doing as part of the coalition against Daesh."

Daesh is another name for the Islamic State of Iraq and the Levant, or ISIL.

National Defence revealed last week that a member of Canada's elite Joint Task Force 2 special forces unit was supporting Iraqi forces when he shot an ISIL fighter who was 3,540 metres away.

That is more than a kilometre farther than the previous record, held by a British sniper who shot a Taliban fighter in Afghanistan in 2009.

News of the shot sparked both accolades and disbelief around the world, but it also prompted NDP Leader Tom Mulcair to rekindle a long-standing debate about whether Canadian troops in Iraq are in combat.

In an interview on Tuesday, Mulcair said he was "more than surprised to hear the Canadian prime minister say that the killing of another human being is something that should be celebrated.

"The skills of our troops are something that we can all recognize, and that's one thing," he said. "But to use the word 'celebrate' in relation to the killing of another human being doesn't reflect my values."

The question of whether Canadian soldiers are in combat in Iraq has swirled since the previous Conservative government deployed the first troops to help fight ISIL in September 2014.

Mulcair repeated his demand that the prime minister come clean with Canadians on the fact the military is engaged in combat in Iraq, despite Liberal promises and statements to the contrary.

The NDP leader noted that Trudeau asserted while in opposition that under the Conservative watch, Canadian troops were indeed in combat when they were calling in airstrikes on ISIL targets and shooting even in self-defence.

"With the information and evidence we have at this point, it is clearly a combat mission by our definition," Mulcair said. "It's also a combat mission by Mr. Trudeau's own definition."

But Trudeau said Tuesday that the sniper was defending Iraqi and Kurdish forces when he took the shot, which is allowed and expected as part of Canada's "advise and assist" mission in Iraq.

"Defending our allies in the coalition has always been an integral part of our training and support mission to the local troops," he said.

"This is completely in keeping with our responsibilities as Canadians, as members of the coalition in northern Iraq, and it will continue to be that way."

The Liberal government is expected to announce in the coming days either an extension or changes to Canada's current mission in Iraq, whose current mandate is set to expire on June 30.

Trudeau also said the government remains "committed to working with the UN" through the eventual deployment of up to 600 peacekeepers, but that Canadians expect the Liberals to make "the right decision."