Protecting the Prime Minister while still allowing him or her to interact with the public is a delicate balancing act for security experts. Recently, two protesters got within arm’s length of Stephen Harper, Canadian Prime Minister.

Two climate-change activists slipped past layers of security at an upscale Vancouver hotel to hold up signs behind Harper while he was on stage at a closed event.

The pair — dressed in black to blend in with catering staff — were quickly removed and no criminal charges were laid, but the incident is being reviewed by the Royal Canadian Mounted Police to see what more needs to be done to ensure the Prime Minister’s safety.