"Any military resources will support but not supplant our police-led plans. Visitors to the UK can continue to expect to see the 'bobby on the beat,' not soldiers on the street," says James Brokenshire, minister for crime and security, by e-mail.
But, he says, "the UK is hosting the biggest and most high profile event in living memory" – so security agencies are leaving nothing to chance.
Last week, authorities detained a suspected British Islamic militant of Somali origin who violated a court order by traveling multiple times to transit stations near the Olympic park.
"It's not so much that the threat is raised [with the Olympics], but the visibility is raised," he says. Even a small attack would be instantly seen around the world and magnified.
Such a situation is tricky for the government, he says. If officials foil attacks, no one will notice and Parliament will wonder why so much money was spent. If an attack gets through, security agencies will be grilled.