One of the first US soldiers to die in Iraq after "liberation" was shot in the head while waiting to buy a coke somewhere in Baghdad. In the coming years, lots of hay was subsequently made about the various factions, Sunni, Shia, Hussein loyalists, and so forth who resisted the US-led invasion and occupation and their power-centred motivations for doing so.
Very little however was said in Western media about the simple fact that unsanctioned armed foreigners, with the powers of domestic security forces, on the streets are the supreme insult to the people who make their homes there. The factional loyalties and associated goals are simply products of a person's social environment and their own take on the situation. The ultimate driver is the imperative to kick out the invaders.
US police, armed and imbued with the authority to enforce laws in Canada? You are goddamned right there are sovereignty worries! Giving foreign police credentials in Canada is an abdication of sovereignty.
That the RCMP is saying they'll be under supervision of Canadian police matters not a whit. It just makes the RCMP look like an extension of US law enforcement.
Canadians very likely won't be setting off bombs, but in doing things like this the Harper regime further delegitimises itself as well as Canadian police. They are only making things harder for themselves and 2015 is a long way off.