Defence Minister John McCallum once again leapt to the defence of the Iltis jeeps being used by Canadian soldiers in Afghanistan Monday, saying they're necessary to allow closer contact with the Afghan people.

Opposition Leader Stephen Harper demanded to know in the House of Commons why the Iltis is still being used when it offers soldiers no protection and was at the end of its service life 10 years ago.

McCallum replied by repeating the words he expressed on CTV's Question Period Sunday, saying the Canadian military can't establish contact with the Afghans in heavily armoured cars.

"To paraphrase Maj.-Gen. Andrew Leslie: You cannot win the hearts and minds of the Afghan people as you speed by in an armoured vehicle," McCallum told the Commons.

Harper countered by saying the hearts and minds of Afghans can't be won by dead soldiers.

McCallum responded that the military has other vehicles besides the Iltis jeeps.

"The commanders on the field have a menu of choices -- armoured vehicles, jeeps, and many patrols on foot," McCallum said. "What we do not need is play soldiers from the Opposition benches dealing unsolicited advice from thousands of miles away to our very capable professional soldiers on the ground."

He admitted though that the Iltis is at the end of its service life and will be replaced by a new vehicle built by Mercedes.

In a video profile presented on the Washington Post website, viewers can catch a glimpse of the type of patrol the Canadian ISAF forces are engaged in. In fact, the video follows Sgt. Robert Short as he conducts a routine patrol near Kabul.

The video was shot only two days before Short was killed along with Cpl. Robbie Beerenfenger by an explosion near Kabul while on patrol last week.

"Today is mainly a presence patrol," Short tells the camera operator. "We're patrolling this path that used to be used by al Qaeda and stuff like that. So, we're just coming here to see if there are any problems."

Short is seen talking to local informants, inquiring about the safety of the area. The mission is, evidently, as much a cultural outreach as it is a military operation.

According to McCallum, it is the kind of mission that exemplifies Canadian expertise.

"We want to reach the hearts and minds of Afghanis. We want to reach the people. And therefore, our commanders on the field don't go out exclusively in armored vehicles," McCallum said in the House of Commons Monday.

The defence minister said Canadians are conducting patrols on foot and in vehicles, depending on the risk.

"This reflects an outgoing desire on the part of many Canadians to help the people of Afghanistan and to communicate with them," McCallum said, adding that there is no reason to change those orders.

The remains of Sgt. Short, 42, of Fredericton, and Cpl. Beerenfenger, 29, of Ottawa were returned to CFB Trenton Sunday.

A memorial service will be held at CFB Petawawa Tuesday. Short will be buried Wednesday; Beerenfenger's funeral is Thursday.

The injured include Master Cpl. Jason Cory Hamilton, 33, Cpl. Cameron Lee Laidlaw, 25, and Cpl. Thomas Stirling, 23. All three are returning home.The soldiers are all members of the Royal Canadian Regiment, 3rd battalion, based in Petawawa, Ont.

The military is still investigating what caused the explosion that killed Short and Beerenfenger last week. Russian defence minister, Sergei Ivanov, in Ottawa, says he considers the deaths to have been caused by terrorists.

McCallum told reporters he's not so sure the explosive device was laid to catch the Canadians. He said it may have been around for years, echoing comments from an Afghan intelligence official quoted in The Globe and Mail Monday.

Abdul Latif, an intelligence official in the district where the blast occurred, told the paper the soldiers were likely killed by an old explosive left over from Afghanistan's 25-year history of war. The explosion happened in an area littered with mines, Latif said.

"I know this area very well. I've worked here for two years and I can tell you it was an accident," the Chardi district intelligence officer said in an interview.

"I've been responsible for this area for two years, and nothing like that (targeting foreigners) has happened from here," Latif said.

CTV's Matt McClure said the Canadian investigation into the explosion has not yet ruled out any possibility.

"The Canadian commanders knew that this area was heavily mined and that's certainly a possibility they're looking at in their investigation, that the mine was there already," McClure told Canada AM Monday.

"But they're still looking at the possibility that it might have been placed there as well."