Prime Minister Stephen Harper says Canada will not sit idly while Islamic State militants in the Middle East threaten to slaughter thousands of innocent people.

"We do not stand on the sidelines and watch. We do our part," Harper said following a meeting with European Union leaders on Parliament Hill Friday.

"That's always how this country has handled its international responsibilities, and as long as I'm prime minister that's what we will continue to do."

"This situation, as I've said before, with a terrorist caliphate occupying in the open a wide expanse of territory, not simply slaughtering and threatening to slaughter hundreds of thousands of people, but this phenomenon is a direct threat to the security of this country," Harper said.

The prime minister's comments come ahead of an expected meeting with his cabinet next week to discuss deploying Canada's CF-18 fighter jets to join a U.S.-led campaign against the Islamic State in Iraq and Syria (ISIS), CBC News has learned.

While Harper has not formally announced that the matter would be put to a vote in the House of Commons next week, Foreign Affairs Minister John Baird said on Thursday that launching airstrikes would amount to a combat mission — which would be put to a vote.

"The prime minister has always been very clear that that would go before Parliament for a vote," Baird told reporters outside the UN in New York.

Britain, Belgium and Denmark on Friday formally committed war planes to the struggle against the extremists.

To date, Canada has sent 69 special forces advisers to Iraq.

U.S. asked Canada for help

Whatever Canada decides to do going forward, Harper said the country has joined the fight against ISIS willingly.

"We will look at whatever the requests are, we will ultimately take our own decisions based on our own capacities and the options we think are realistically available to us.

"But that said, there is no reluctance here," Harper said.

Canadians learned of a U.S. request for further military contribution in the fight against ISIS when Harper told a business audience in New York on Wednesday he had received a letter from the U.S. outlining its needs.

Today, Harper took issue with media reports suggesting the U.S. did not ask Canada for help but that Canada offered it unprompted by the Americans. 

"Is this seriously suggesting that Canada is dragging the United States into a military conflict? Let's be serious here."

Harper explained that Canada is responding to U.S. requests for help in Iraq, and not the other way around. 

Moments before Harper spoke to reporters, Bruce Heyman, the U.S. ambassador to Canada, took to Twitter to clarify the matter.

"We asked #Canada to join the fight against #ISIL and we are grateful for Canada’s steadfast commitment," Heyman said.

The U.S. ambassador added, in subsequent posts on Twitter, that "Canada has been a critical partner in both the military and humanitarian effort in Iraq."

"Together we are focused on dismantling and ultimately destroying #ISIL."