The media was barred from photographing or interviewing Canadian soldiers as they left Monday for a training mission in eastern Europe, a broadening of a ban imposed last fall at the height of concern over Islamic State terrorists.

Despite having been invited to a photo opportunity, the media was prohibited from taking pictures of the faces or name tags of the 125 troops who left Garrison Petawawa, Ont., for a three-month exercise involving NATO troops in Poland and Latvia.

The ban was also in place later Monday as another contingent departed from the country's largest military air base in Trenton, Ont.

Lt. Jean-Francois Carpentier, a Canadian Armed Forces spokesman in Petawawa, called the restriction a "force protection measure," but could not say why it was applied to soldiers not involved in an active combat mission.

Troops who took part in last year's NATO exercises, including the Baltic air police mission, were not subject to the restriction.

Photo ban a 'precautionary measure': DND

Carpentier referred questions to the Ottawa-based Canadian Joint Operations Command, which did not respond directly to a request for comment.

Instead, in an emailed statement, a spokesman for National Defence confirmed the ban and said security demands were "evolving," with the safety and well-being of personnel — both uniformed and civilian — top of mind.

"As a precautionary measure, it was decided prudent not to disclose the identity of CAF personnel deployed or about to deploy by avoiding having their face photographed or their name disclosed to the media and the general public at large, due to current force protection assessments," said Dan Le Bouthillier.

Le Bouthillier did not say if the ban applies to all overseas missions, including humanitarian deployments; if it is permanent; or if it was imposed in response to new, specific threats against soldiers.

"The (Canadian Armed Forces) will always err on the side of caution when it comes to the safety and security of our personnel and their families," Le Bouthillier added.

The military enforced a similar ban last October as crews left to join the combat mission in Iraq against the group known as the Islamic State of Iraq and the Levant — measures that were reinforced days later following the murders of two soldiers by apparent Islamic extremists.

Since the latest deployment is not a combat mission, and not related to terrorism, the NDP's deputy defence critic demanded the government clarify its policy.

Restrictions 'popping up more and more': NDP

"This restriction seems to be popping up more and more, yet the minister has failed to explain why to Canadians," said Elaine Michaud.

"Of course, we all want to keep Canadian soldiers out of danger, but the minister must be clear with Canadians: Is this a policy in response to a specific threat, or are there other reasons for these new rules?"

Media access to the country's soldiers and Canada's military institution overall has been slowly eroding in recent months.

The media was barred from setting foot last fall on the air base in Kuwait from which CF-18s jetfighters, CP-140 surveillance planes and C-150 tankers were conducting their air campaign in Iraq.

The military said the Kuwaitis had not given permission for media access.

As a result, Canadians usually only hear news about the Iraq combat mission by way of a carefully vetted media briefing at National Defence headquarters, or statements delivered by the government in the House of Commons.

All of the publicly released footage and imagery from the combat mission is shot and distributed by the military's own media arm, known as Canadian Forces Combat Camera.