The deployment of an infantry platoon was approved by the Harper government on Oct. 16, 2012, according to internal defence department documents obtained by The Canadian Press.
Three-dozen soldiers arrived in Brazil last April to be embedded and train with that country's 44th Motorized Infantry battalion, the Brazilian joint operations centre reported in an online article that included photos of the arriving Canadians.
Although it has been the subject of a couple of speculative media stories in this country, the partnership and the mission won't be formally announced until Wednesday, a little over one day before the boots hit the ground in Haiti.
Defence Minister Peter MacKay and consular affairs minister Diane Ablonczy, who is also responsible for the Americas, are expected to announce the deployment, which will run six months.
A senior defence source said the United Nations only signed off within the last week on the unusual request to add Canada to the contingent.
The idea of teaming up with Brazil, the largest contributor to the UN stabilization mission in Haiti, has been floated around National Defence headquarters for two years and was pitched as a way to increase bilateral ties with the emerging economic power.
The fact the government has kept quiet — and not pre-promoted — what would be a politically appealing move amid a blizzard of bad news military procurements has left defence observers scratching their heads.
"I find it surprising Canada wouldn't be more forthright ahead of time about this positive development," said Walter Dorn, an expert on peacekeeping at the Royal Military College. "It helps Haiti. It helps the United Nations, the United States and Brazil."
Liberal defence critic John McKay said Parliamentarians and the public have been kept in the dark, and there was a time contributions like the one in Haiti would be either signalled — or discussed in front of a committee beforehand.
The last supporting mission Canada undertook, helping French forces in Mali, leaked out following a tweet from by the president of that embattled country.
"The mission to Haiti is not highly classified. We're not attacking anybody. We're going to help the Haitians," said McKay. "So why has this come together in such a clandestine fashion?"
Military sources said negotiating the terms of the deployment with Brazil was time-consuming and UN approval was also not assured.
Even still, McKay was incredulous that the public is only learning details six months after cabinet formally approved it.
The Conservatives have tried to distance themselves from the country's peacekeeping legacy and that may have something to do with the hesitancy, Dorn said.
"The government has placed a much lower priority on providing Canadian Forces personnel to peacekeeping than any other government since the Second World War," he added.
The troops will be drawn from the Royal 22e Regiment, based in Valcartier, Que.
There are 6,443 international troops in Haiti and an additional 2,661 police officers conducting training under the United Nations flag.
After sending a battalion of the Royal 22e Regiment to deliver humanitarian relief in Haiti following the 2010 earthquake, the Canadian presence was scaled back to 141 police officers, 25 corrections officers and five military staff officers.
Note to readers: This is a corrected story. A previous version had an incorrect number of international troops and police in Haiti