That's a problem that has to be dealt with in pretty much any historical event, even in official documents.
However, this one seemed relatively genuine to me, and you have the opportunity to judge for yourself.
IIRC, it was in one of these that the comment was made, and apparently they're now available on YouTube
http://www.channel5.com/show/secrets-of-the-sas-in-their-own-words
Incidentally, it would be interesting to find out how you know such intimate details of classified operations
"for a certain fact".
Doesn't seem much like something that would provoke a Brazilian DoW. I mean, it's just the RN sinking enemy ships.
(Unless you mean a Brazilian CV, not sure if they had one.)
Sadly, I don't know the size of the brazilian navy at the time, neither of the army and I cannot find this info online
At the best they could make a strike force led by the Carrier Minas Geraes and tried to break the british blockade of the falklands, but that's it
Having been damn near killed by SAS incompetence on Mount Kent in 1982 (they reported it empty, so my troop and I were heli-borne in to grab it; it turns out that it wasn't quite empty, and the SAS patrol had missed a half battalion of Argentine infantry on the mountain), I'm a little less inclined to regard the SAS as the supermen their publicity machine makes them out to be.
Elsewhere, during South Georgia (and outside of my personal experience) the SAS ignored the direct advice of Marines trained in MAW, decided they knew better, and the consequence was three downed helicopters for no tactical benefit.
Less directly, I've had the misfortune to proof read several books published by supposed SAS types. Having been a Royal Marine Commando for a while (1969-1982), I know a bit about tactical operations. I've been less than convinced by a number of the tactical descriptions given in several of these. I can't say for sure whether the ex-SAS tag given to some of these authors is somewhat ambitious, whether the descriptions were deliberately made comical to anyone with the slightest knowledge of these things (for example, burned on my mind is a description of the SAS being surprised to discover that it gets cold at night in the desert), or whether the ex-SAS described really were incompetent.
Regiao sol do Brazil
If Brazil moves sufficient numbers of troops to its Southern Provinces, they could help defend Rio de Janero against British Invasion.
With Uruguay turning a blind eye, the Brazilian Air Force and Navy could patrol the approaches to Northern Argentina, preventing British troops from landing.
If Uruguay helps patrol those waters, even better!
Even if Brazilian and Uruguayan troops never cross the Argentine border, they can still substantially reinforce Argentine defences.
Regiao sol do Brazil
If Brazil moves sufficient numbers of troops to its Southern Provinces, they could help defend Rio de Janero against British Invasion.
With Uruguay turning a blind eye, the Brazilian Air Force and Navy could patrol the approaches to Northern Argentina, preventing British troops from landing.
If Uruguay helps patrol those waters, even better!
Even if Brazilian and Uruguayan troops never cross the Argentine border, they can still substantially reinforce Argentine defences.
I have long suspected that most of those books and films about (SEALS, SAS, SBS, SAS, Green Berets, Rangers, Fallschirmjagers, Delta Force, etc.) were part of a larger dis-information campaign.
First, tales of heroic deeds mean more medals awarded to soldiers in those units.
Secondly, tales of heroic deeds help with the next round of funding.
Thirdly, tales of heroic deeds help attract better quality recruits.
Fourth, tales of heroic deeds scare the enemy.
Fifth, inaccurate tales of heroic deeds spread confusion among the enemy.