London flexes Olympic muscle

LESTER HOLT, anchor: The London Olympic Stadium formally opened this weekend, now with just 82 days before the Summer Games begin. In this coming week, the continuation of a huge military exercise aimed at making sure the games are safe and secure. NBC 's Stephanie Gosk has the story tonight.

STEPHANIE GOSK reporting: HMS Ocean , the largest warship in the British fleet , squeezing up the Thames River to London for the Olympic Games . The British military flexing its muscle for the world to see. Typhoon fighter jets, surface-to-air missiles, high-speed boats. There are no known plots targeting the games, say commanders, but they need to be ready.

General NICK PARKER (British Military): There's a range of threats. We're looking at the extreme threats, the highest impact, but the most unlikely.

GOSK: The military is needed to stop worst-case scenarios, like a 9/11 style air attack on the Olympic Park . There are eight of these Lynx attack helicopters on HMS Ocean . Each one will have a sniper. If there's a threat from a low-flying aircraft, they could be flown in to shoot it down. But it isn't just helicopters. Surface-to-air missiles will provide another layer of defense this summer. Earlier this week, the British military shocked some London residents with leaflets, warning that missile systems might be placed on their rooftops.

Mr. BRIAN WHELAN (London Resident): I assume they have security in hand. And I was never expecting it to come to this, though. I was never expecting to wake up to a leaflet saying that I was going to become a military base .

GOSK: Security is a huge operation, from missiles, to police patrols, to bag inspections at the park. With a huge price tag, an estimated $1.8 billion. That includes this week's military exercise , a rehearsal that is also about sending a message.

Professor MICHAEL CLARKE (Royal United Services Institute): The exercise is designed to reassure the public and the Olympic movement that security is taken seriously. And it's also to create a deterrent to anyone who's going to have a go, that if they do, they'll probably die.

GOSK: A large scale show force of force now, commanders say, so it won't be needed this summer. Stephanie Gosk, NBC News, London .