U.S. Defence Secretary Ash Carter challenged NATO members Thursday to accelerate efforts in the fight against the so-called Islamic State, as alliance defence ministers wrapped up two days of meetings in Brussels.

The meeting comes only a few days after Canada announced it will pull its six CF-18 fighter jets from the air campaign against ISIS, while increasing the number of military trainers it has on the ground.

Harjit Sajjan, Canada's minister of defence, spent much of the two-day meeting explaining Ottawa's decision to allies.

"When you actually start putting more of your trainers on the ground to assist local security forces, that's not stepping back, that's stepping up," said Sajjan.

On a conference call Thursday with Canadian journalists, Sajjan added that feedback on Canada's expanded anti-ISIS plan from NATO allies has been "complimentary."

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NATO Secretary General Jens Stoltenberg speaks during a media conference at NATO headquarters in Brussels. NATO countries, including Canada, are sending three warships to the Aegean Sea on the request of Turkey, Germany and Greece to stop migrant smuggling. (Virginia Mayo/The Associated Press)

Sajjan said U.S. Army Lt. Gen. Sean MacFarland commended Canada for being "forward looking" in its approach to expanded intelligence services.

"We have set the example for what the actual mission needs," said Sajjan.

NATO Secretary-General Jens Stoltenberg echoed these remarks on Canada's decision to pull out its fighter jets.

"The message is very clear that Canada will continue to support the global coalition fighting ISIL," said Stoltenberg, using another acronym for the group that calls itself Islamic State in Iraq and Syria, or the Levant.

Fighting displacing more people

The allied bombing campaign in Syria has displaced about 10,000 people, according to aid agencies.

The advance of Syrian troops into Aleppo facilitated by Russian airstrikes against Syrian rebel positions has further complicated the anti-ISIS fight. Thousands of refugees have fled for the Turkish border and the humanitarian situation in and around Aleppo is rapidly deteriorating.

"Russia needs to be a more constructive partner with this and more focused on targeting ISIL in Syria and helping to bring this conflict to some type of resolution, where we can start a political dialogue in a more meaningful way," said Sajjan, adding that Russian bombing of cities only adds more fuel to ISIS.

NATO's European commander ordered three warships ― including one from Canada ― on Thursday to patrol the Aegean Sea for people-smuggling operations between Turkey and Greece.

Turkey, in a joint request with Greece and Germany, asked its NATO partners to intervene in the refugee crisis to help tackle the smuggling networks carrying refugees to Greece.

"It's very refreshing to see the response from NATO for the migrant crisis," said Sajjan. "There have been a lot of lives that have been lost, so this will help local police forces do their jobs."

The warships, under German command, will conduct surveillance work to help end Europe's migrant crisis.

"[The warships]...will be tasked to conduct reconnaissance, monitoring and surveillance of the illegal crossings," Stoltenberg said.

NATO has also agreed to a U.S. request for surveillance planes to be used as relief in the air campaign against ISIS.

With files from Margaret Evans and Ramisha Farooq