Prime Minister Stephen Harper and U.S. President Barack Obama agreed during a telephone conversation Tuesday that “a firm response” to the use of chemical weapons against civilians in Syria is required.

According to a statement about the conversation released Tuesday afternoon by Harper’s spokesperson, both leaders agreed that the use of chemical weapons is “an outrage.

“Both leaders noted efforts by the Syrian regime to delay the work of the UN chemical inspection team, suggesting the regime is attempting to obscure evidence of its actions. Both leaders agreed that significant use of chemical weapons merits a firm response from the international community in an effective and timely manner.”

The conversation occurred as world leaders appeared to be readying for a military intervention in Syria, particularly in response to reports of chemical weapon attacks against civilians in a Damascus suburb on Aug. 21.

Neither United Nations inspectors, who were at the site of the alleged chemical attack Monday after being delayed by sniper fire, nor the Americans have issued a formal declaration confirming that a chemical weapons attack occurred.

However, on Monday, U.S. Secretary of State John Kerry said it was “undeniable” that chemical weapons had been used, while Baird did not use the word “alleged” when referring to a chemical weapons attack, as he had in statements he made last week.

U.S. Defence Secretary Chuck Hagel made clear Tuesday that American troops stand ready to strike targets in Syria once a chemical weapon attack has been confirmed. Hagel said U.S. forces have “moved assets” to the region to allow for any action that Obama may authorize.

British Prime Minister David Cameron has called an emergency session of Parliament for Thursday, when lawmakers are expected to vote on joining an international military mission. French President Francois Hollande said Tuesday that France is “ready to punish those who took the heinous decision to gas innocents.”

A brief statement from the White House said, “The United States and Canada strongly oppose the use of chemical weapons, and the President and Prime Minister pledged to continue to consult closely on potential responses by the international community.”

However, a spokesperson for Foreign Affairs Minister John Baird reiterated comments made Monday, saying again on Tuesday that, “It is premature to discuss recalling Parliament.”

Rick Roth said, “Canada is outraged by the use of chemical weapons in Syria,” and acknowledged that although a political solution is desired, it is “becoming more and more difficult as the crisis enters a dangerous new phase.”

Baird’s office announced Tuesday evening that he has spoken to Opposition Leader Thomas Mulcair and Liberal Leader Justin Trudeau, and planned calls to the leaders of both the Bloc Quebecois and Green Party.

CTV’s Mercedes Stephenson reported that Baird’s office “will not get into details of the calls.”

Mulcair told reporters Monday that Parliament must be recalled if Canada is considering joining an international military mission, but said Canada should only get involved if such a move was authorized the United Nations.

But the U.S. appears to be preparing for military action based on its own intelligence.

The UN inspection team remains in Syria to investigate, but their work Tuesday was delayed.

A U.S. Department of Defense official said that Syria was discussed at a two-day conference in Jordan that had been previously scheduled. 

Chiefs of staff from a number of countries, including Canada, attended the meeting, hosted by the U.S. and Jordan.

“The Chiefs of Defense in attendance expressed deep concern over the use of chemical weapons in Syria and discussed the ongoing crisis and the associated challenges to the region,” the Department of Defense official said in a statement.

“Though not a planning conference and scheduled since June, the event provided a timely opportunity for the defense chiefs to meet amidst the latest challenges and share perspectives on issues such as the makeup of opposition forces and short- and long-term impacts of the growing refugee crisis, as well as concern for the spread of sectarian violence in the region." 

Meanwhile, Baird is scheduled to meet in Montreal Wednesday with George Sabra, president of the Syrian National Council, the main Western-backed opposition group in Syria. Sabra called on the international community to step in with a military strike to stop attacks on civilians and provide humanitarian aid to help the more than one million refugees that have fled the crisis.

Sabra told CTV’s Canada AM Tuesday that his group considers Canada “one of our best friends,” and so wants Baird to commit to joining an international response, whatever action it may take.

“I want to hear from him that Canada is a part of the coalition, the international coalition which intends to do its best to stop the killing in Syria,” Sabra said.

“And send a clear message to the Syrian regime that they can’t escape from punishment after the massacre beside Damascus, where there are more than 1,600 victims, most of them are women and children.”

Sabra also wants Canada and other Western powers arm the rebels seeking to oust Syrian President Bashar al Assad.