NATO's chief military adviser, Canadian Gen. Ray Henault, has urged Canada to contribute to the mission in Afghanistan for as long as possible.

Henault, a former Canadian chief of defence staff, held a news briefing in Ottawa on Thursday shortly after arriving to chair a conference of 26 NATO generals.

He said the alliance is aware of the domestic debate over Canada's participation in the mission in Afghanistan. Roughly 2,500 Canadian soldiers are serving in the violent southern Kandahar region. 

Opposition leaders have demanded Prime Minister Stephen Harper formally announce Canada will end its combat mission in the country in February 2009.

"At NATO, we are aware of the discussions that have been ongoing in Canada with respect to the continuation of the mission," Henault said. "We understand the decision to carry out operations is a national decision.

"We encourage all countries, including Canada, to provide assistance as long as possible."

Henault said he doesn't know how long NATO will be in Afghanistan.

"It's an end state. We will go as long as possible to satisfy the requirement for what we have signed up to," he said.

The chiefs of defence, their wives, and senior military staff from the alliance's headquarters in Brussels arrived in Ottawa Thursday afternoon.  They will attend a state dinner with Gov. Gen. Michaëlle Jean on Thursday night in Ottawa before flying to Victoria for a series of meetings.

Canada’s chief of the defence staff, Gen. Rick Hillier, will be the official conference host.

Henault said delegates will discuss current missions in Afghanistan and Kosovo, as well as the NATO Response Force, the alliance's rapid reaction unit.

The meetings will wrap up on Saturday, with the conference formally ending on Sunday.

NATO's top generals meet three times a year; twice in Brussels and once in a host nation. Canada last hosted the meeting in 1997.