A decades-old peacekeeping operation may be threatened thanks to a raft of violence caused by Islamic State-linked groups in the Sinai Peninsula.

The violence has even pushed Fiji, which had sent 57 peacekeepers to the operation, to pull its contribution — one returning peacekeeper called the region, which sits between Egypt and Israel, a "real live battle."

Those Fijians were, until the end of May, part of a 1,600-strong force charged with maintaining a decades-old buffer zone between Israel and Egypt in the desolate region. They've been there since 1981 under the direction of the Multinational Force and Observers (MFO).

But things have gotten hairy recently, with IS' Sinai province ramping-up attacks.

"We could hear gunshot and shells blowing up. We were in between real live battle. We had full armoury, bullet vests, metal helmets and loaded weapons 24/7," a Fijian peacekeeper told the Fiji Sun on Monday, after returning from the mission.

The peacekeepers from the tiny island nation came home after several bases they staffed were shut down over security concerns.

Canadian peacekeepers stationed at the MFO base. (MFO)

The majority of the peacekeeping contingent are from the United States military, but peacekeepers for the MFO also hail from Australia, Canada, Colombia, the United Kingdom, and elsewhere. The force is currently being commanded by Major General Denis Thompson, on loan from the Canadian military.

US Defense Secretary Ash Carter opened the door to ending the mission altogether in April, with Egyptian media reporting that the US was considering replacing the peacekeepers with an electronic monitoring system in the sparsely-populated area.

The Canadians, meanwhile, signaled that their mission would continue, despite the fact that its 70 personnel at the base had been moved from the north camp — which had been the target of many of the attacks — to its south base. Spokespeople for both the foreign affairs ministry and the defense department confirmed that there were no plans to bring the peacekeepers back home.

"We continue to see our participation to the MFO as a key element of our broader engagement in support of peace efforts in the Middle East," said a spokesperson for Global Affairs Minister Stéphane Dion.

Harjit Singh Sajjan, Canada's defense minister, told VICE News on Tuesday that he's "on top" of the mission.

"The mission is becoming more challenging because of the threats, but I stressed on the Egyptians to do more, and they have been doing more," said Sajjan, adding that he's also spoken with Carter.

Asked specifically whether Canada's rules of engagement permit its peacekeepers to return fire, Sajjan confirmed that they do.

"When it comes to the right to self-defense, it will always be there," he said.

A magazine prepared for the peacekeepers also shows photos and details of security upgrades to the base that have been added in the last year.

Since 2011, in the chaos of the Egyptian revolution, jihadist groups like Ansar Bayt-al Maqdis have stirred violence near the MFO headquarters. In 2014, the group pledged allegiance to Abu Bakr al-Baghdadi, and declared themselves Wilayat Sinai — the Sinai province of the Islamic State.

The group is responsible for a string of attacks that have killed dozens of Egyptian police, soldiers, and civilians. They also claimed responsibility for the bombing of a Russian jet that claimed the lives of all 224 onboard.

As the group gets bolder, the threat to the MFO is growing.

According to a briefing note prepared for Canada's foreign affairs minister last November, obtained by VICE News under Canada's access to information laws, "the threat environment has changed over the summer months of 2015."

The note reads that the MFO had had been hit by mortar and sniper fire in two different attacks over the summer of 2015, which injured an American soldier.

On September 3, 2015, an improvised explosive device hit a vehicle carrying two Fijian peacekeepers. A second IED hit an American vehicle which responded to the attack. All six were injured, but survived.

"While partner nations, including Canada, have increased unilateral force protection at the MFO, there is increasing concern among troop-contributing countries regarding the security situation in the Sinai," the note reads, adding that the United States had added an additional 75 troops to the base.