OTTAWA -- Canada is considering a NATO request to send police trainers to Afghanistan, three years after the military mission officially ended, Defence Minister Harjit Sajjan says.

The request came from the U.S. through NATO, and could involve either civilian police trainers like the RCMP, or military trainers working with Afghan police, a defence official added.

Sajjan says Canada is "looking at all aspects of support" for Afghanistan -- though he ruled out the country as a destination for Canadian peacekeepers since it's not a UN mission.

"We've actually had an ask, but it was for police trainers in Afghanistan," Sajjan said in an interview with Evan Solomon, host of CTV's Question Period.

"We are actually still committed to Afghanistan. We've provided the funding, whether it's for development" or salaries for security forces in the country, he said.

From 2014 to 2017, Canada committed $227 million in international development programs in Afghanistan, and $330 million from 2015 to 2018 in support for the Afghan National Security Forces, which include the Afghan National Army and the Afghan National Police.

Sajjan says Canada can't look at any country in isolation.

"This is what coalitions are for, multilateralism is for. I'm in constant discussions with my counterparts on all the various threats, whether it's at NATO or the counter-DAESH meetings," he said, using another name for the Islamic State.

"We will always look at the various requests, but the thing is when we have the discussions, it's not about just one nation ... stepping up and saying, 'I'll do this.' It's about working together."

Peacekeeping mission 'on the table'

Last August, Sajjan announced Canada would devote 600 troops and $450 million over three years to a peacekeeping mission. He later toured several African countries and said he would announce the mission by the end of the year, but six months into 2017 there is still no word on where it will be.

A mission somewhere in the world "is on the table. We're committed to peace support operations," Sajjan said, citing a change in leadership at the UN and the new president of the U.S. as reasons for the delay.

"I've had discussions with [the UN], things looked very good... It's not about just sending troops. How can we now look at the current environment and bring our unique skillset to the table?"

While Sajjan ruled out Afghanistan as a peacekeeping destination, Richard Fadden, a former top civil servant at the Department of National Defence and former national security adviser to the prime minister, says having shed blood and spent a great deal of money on the country, it would make sense to return.

"Afghanistan has deteriorated quite a bit over the last few years," he said.

"I think if we were going anywhere to make a contribution, broadly speaking, to peace in the world, Afghanistan would be a good place to go. There are not that many other places where we could make a difference that would not result in ... our being involved in a massive quagmire."

Retired Gen. Tom Lawson, a former chief of the defence staff, says he prefers Afghanistan to some of the African countries Canada could end up, like Mali or the Democratic Republic of Congo. Both would carry significant risks for Canadian Armed Forces personnel.

"If it keeps us out of other places, [like] in Africa, I'd be delighted as a former chief of defence," Lawson told Solomon.

"So Afghanistan is a place that Canadians have invested both money and blood. We continue to invest money there. If a return was in Canadian defence future, it would be to a familiar zone."

Over the 12-year mission, 158 Canadian troops were killed, as well as a diplomat, a journalist and two civilian contractors, according to a tally by The Canadian Press.