The Conservative-dominated House of Commons has voted to extend Canada’s military campaign against Islamic State militants in Iraq and expand the mission into Syria.

MPs voted 142-129 to extend the mission until the end of March 2016, and authorize airstrikes in Syria. The extension does not include any additional troops or military aircraft.

An NDP amendment to the motion, calling for an end to Canadian Forces’ participation in the airstrikes and combat “as soon as possible,” as well as asking for a boost in humanitarian aid for refugees, was defeated. The Liberals also voted against it.

Last fall, the House voted to send 69 special forces soldiers, 600 military personnel, CF-18 fighter-bombers and two surveillance planes to fight ISIS in Iraq. Since then, the government has said that Canadian troops have been successful in dismantling numerous ISIS targets and weakening the terror group’s manpower and resources.

Monday’s vote came after several hours of debate in the House since last week. Opposition MPs slammed the plan to expand airstrikes into Syria and questioned whether there is a legal basis for it. The NDP and the Liberals did not support the Conservative motion, arguing that by getting involved in Syria, Canadian troops would be assisting the country’s brutal regime.

The Conservatives have said that airstrikes in Syria are legally justified and denied that Canadians would be assisting Syrian President Bashar al-Assad. Defence Minister Jason Kenney and others have said that ISIS must be forced out of its base in eastern Syria and that Canada has a duty to act.

We must act to protect Cdns against the threat of terrorism at home & abroad. I'm pleased the HoC has passed our motion to do just that. — Stephen Harper (@pmharper) March 31, 2015

Conservative MP Ted Opitz also told the House Monday that ISIS poses a “clear” and “continued” threat to Canada.

But NDP Leader Thomas Mulcair accused the Harper government of misleading the House and Canadians about the Iraq mission and said that Canada “doesn’t have the legal grounds to conduct air strikes in Syria.

“I asked the prime minister repeatedly what his legal basis was for this dangerous new escalation,” Mulcair told the House shortly before Monday’s vote.

“Depending on the day, and in fact, depending on the time of day, this government gives differing and contradictory legal grounds for expanding the prime minister’s war.”

Liberal Leader Justin Trudeau also questioned the legitimacy of an expanded mission, and accused the Tories of “steadily and stealthily” drawing Canadian troops into ground combat in Iraq.

He also said that outrage over the atrocities committed by Islamic State militants should not “cloud our judgement.”

Kenney, meanwhile, accused Trudeau of “shambolic, fatuous…flip-flopping,” during the debate on Monday.

The NDP and the Liberals have said that the government should be doing more to assist Syrian and Iraqi refugees as part of the mission. Trudeau called on Ottawa to commit to accepting 25,000 Syrian refugees.

This month, the Conservative government finally fulfilled a 2013 promise to resettle 1,300 Syrian refugees by the end of last year.

On Tuesday, diplomats from around the world are expected to meet in Kuwait to discuss easing the humanitarian crisis in Syria.

With files from The Canadian Press