"I asked the prime minister straight up in September whether this was a combat mission, whether Canadian troops would be involved in combat. I got a categorical answer, and the answer was no," Mulcair told reporters during an event at a Toronto child-care centre Tuesday.
"I specifically asked him in the House of Commons whether or not Canadian Forces would be targeting troops on the other side," Mulcair said. "He did not tell the truth."
During a briefing in Ottawa on Monday, Brig.-Gen. Michael Rouleau, the commander of the Canadian special operations forces command, revealed that Canadian Forces trainers working with Iraqi troops came under "immediate and effective mortar fire" from ISIS and responded with sniper fire, "neutralizing the mortar and the machine-gun position."
The troops had been in a planning session several kilometres behind the front lines, Rouleau said, but had moved up to better see what they had discussed.
He characterized the exchange of gunfire as consistent with the inherent right of self-defence and suggested an incident like this wouldn't have been unusual even in past Canadian peacekeeping missions.
"We have always been clear that while this is a low-risk mission, it is not without risk and our forces on the ground will protect themselves if fired on in the course of carrying out their mission," Prime Minister Stephen Harper's spokesman, Jason MacDonald, said in a statement.
Liberal MPs gathered in London, Ont., for a caucus retreat this week echoed Mulcair's concern that the government needed to clarify the exact role Canadian troops were playing on the ground.
"The prime minister made assurances to Canadians and to the House that as we found out yesterday were not exactly the truth," Liberal Leader Justin Trudeau told reporters Tuesday.
"The prime minister needs to come clean with Canadians on what's going on and why he was lacking in forthrightness with Canadians."
"The government is going to argue obviously that this is not a combat mission in the sense of Canadian soldiers going on the offensive," said foreign affairs critic Marc Garneau.
"They are clearly on the lines, in some cases directing airstrikes, and this is something I think many Canadians did not realize," he said. "I think for some people yesterday that was a surprise."
When Parliament voted last fall on the deployment of aircraft for a bombing mission, Liberals were not supportive, suggesting the appropriate Canadian role to counter the ISIS threat would focus more on humanitarian assistance, training and logistics support.
"It has the appearance of mission creep," said defence critic Joyce Murray. "There appears to be a change."
No front-line role?
While information from Kurdish forces early on suggested Canadian trainers may call in airstrikes, Harper specifically said ground troops would not be accompanying the Iraqi forces into combat.
Now they've exchanged sniper fire.
"The fact that it led so many newscasts indicates that Canadians were surprised — that we thought we were sending aircraft on a combat mission, on a bombing mission, and we suddenly find our ground forces are exchanging fire," said Liberal House leader Dominic LeBlanc.
"The government asked Parliament for a mandate for one sort of mission, and if they've decided now to do a different kind of mission, they should at least have the decency to come back and force their own MPs to vote in favour of the change of the mission," LeBlanc said.
Not every Liberal was surprised by Monday's revelation.
"Everyone expects that the Canadian military, even though they're there for the express purpose of training, if fired upon, they have to defend themselves. And it wasn't an aggressive stance, it was a defensive stance when fired upon and I think the public would be onside with that," said public safety critic Wayne Easter.
"We've asked for a review [of the mission] in six months," he said, adding that since Parliament made its decision, Liberals have supported the troops.
"We will see where we go at that point of time."