The global super-event is an ideal opportunity for terrorists due to its visibility, size and number of people involved, according to experts from Loughborough University, the Air Force Institute of Technology, USA, and the Instituto Tecnológico da Aeronáutica, in Brazil.
Professor Gilberto Montibeller, who led the research team, said the Games differs from other well-studied counter-terrorism analyses because the defensive measures are purposely made public to increase deterrence against terrorist attacks.
In a new paper, published in the journal Risk Analysis, the team identifies a system of visible defensive measures, such as sniffer dog patrols and anti-missile protection, to mitigate the threat of various forms of attack – for example, bomb vests and projectiles.
The countermeasures are defined as possible scenarios with the attacker’s odds of success assigned to each possible choice of venue target in a counter-terrorist decision model.
Prof Montibeller said: “This is a type of game-theory model in which the defender moves first. The attacker then observes the defender's move before then deciding what to do next.
“For example, the defence would plan to use an anti-missile system to protect the Olympic stadium.
“The attackers see the anti-missile system and give up the use of a missile and consider instead bringing a bomb-vest.
“The defence would put in place sniffer dogs. So, the attackers would give up the idea of a bomb-vest and choose other means of attack.
“This goes on until attackers give up any kind of attack.
“The advantage of using this method is that the defence can understand the strategy of the attacker and use efficiently resources for protecting the sports venues.”
The model was validated with security experts responsible for the 2016 Olympic Games in Rio de Janeiro.
The measures deployed in Brazil included inspections, explosive detectors, sniffer dog patrols, antiaircraft batteries, command and control centres, closed-circuit camera systems, fences, and obstacles at stadiums, hotels, and tourist attractions.
However, the cost of these deterrents totalled more than $1.2bn BRL (£278 million).
The research team showed in the paper that a more rational allocation of resources could have provided the same level of deterrence with less expenditure.
The new decision support method allows organisers of mega-events to calculate the chances of the most probable attacks and deploy measures accordingly, at a much lower cost.
“It is possible that high levels of deterrence can be achieved with a smaller budget increasing the value-for-money in these defensive investments,” said Prof Montibeller.