The mayor of London and the Metropolitan Police Commissioner both warned today that a "lone wolf" attack during the Olympic Games is a distinct security concern.
Boris Johnson met Commissioner Bernard Hogan-Howe as he was shown around the Met's specialist operations room in Lambeth, south London.
The facilities are the nerve centre of the Olympics policing operation, where officers will monitor the situation on the ground outside the Games venues side-by-side with members of the military, emergency planners and the ambulance service.
Both men admitted a lone wolf terrorist attack is a concern in the wake of last week's midnight cinema massacre in Aurora, Colorado, which saw 12 people shot dead at a screening of the latest Batman film.
Speaking after the visit, Commissioner Hogan-Howe, 54, said: "Certainly in terms of a lone wolf, it is always a possibility, an individual who, as we have seen in America, gets hold of a firearm and does some terrible things.
"But we do have things in place to prevent that happening.
"First of all we work with the security services to identify those people that we think are at a risk of doing that.
"And then we have good systems in place to make sure, should the worst happen, we deal with these things quickly.
"It's an open democracy, it's a free society, so there are some limits to what we can do to intervene but I think we have got a good plan in place and good continuous planning, and we have tried to remove as much of the threat as we can."
Johnson, 48, claimed he was "re-reassured" after visiting the specialist operations room, which he said was imbued with a "moon-shot buzz" three days ahead of the Olympics opening ceremony.
He joked with officers in the CCTV monitoring suite, who have access to 10,000 cameras all over London, saying that things seemed to be going "worryingly well".
But asked about the threat of a lone wolf attack, he added: "Nothing you can do here can make sure that any city in this country is completely safe.
"What you can do is manage the risk, and everybody will appreciate that we are working extremely hard to make sure of that."
After being introduced to members of the Specialist Operations Room by Olympics gold commander Bob Broadhurst, the mayor said: "I have never been in any doubt that we are in very good shape to deal with this operation, but what is so good about this place here is that it brings together all the agencies involved in security.
"I have been here lots of times over the last few years and I have never felt a buzz like this, this is like a moon-shot.
"These people are all very focussed, I was going round talking to them and they were so busy it was sometimes hard to distract them and say 'hi' - they're on the case."