From The Brockville Recorder Times:
MONTREAL (CP) - Quebec provincial police are holding a news conference later today to explain why three of its agents played the part of protesters at this week's North American Leaders' summit in Montebello, Que.
After originally denying it, the Quebec force has admitted the undercover officers were involved in the protest after a video clip of the trio showed up on the popular website, Youtube.com. But Quebec provincial police are denying they were attempting to provoke protesters into violence.
Rather, they say the three officers were planted in the crowd to locate any protesters who were not peacefully demonstrating.
The force will hold the news conference at 3:30 p.m. at its downtown Montreal headquarters.
Public Safety Minister Stockwell Day has already rejected opposition calls for an inquiry.
Presumably, the cop with the rock was offering it to other protesters. If any of them had actually thrown it, he would have stepped in.