SURFACE-TO-AIR missiles have been set up on Blackheath and the Royal Navy's largest vessel has moored at Greenwich.
The stark images of militarisation will be broadcast around the world as the Navy and RAF prepare for this summer's Olympic games.
Rapier surface-to air-missiles, last used in the Falklands, have been set up on Blackheath - described by Air Vice-Marshall Stuart Atha as a "first class site".
The Starstreak High Velocity Missile system will also help protect London 2012 from potential airborne threats this summer.
They have been placed on Blackheath this weekend as the RAF continues to finalise plans to position the missiles in six sites in east London. Oxleas Meadow has also been selected as a location for the missile defence systems.
The missiles can offer protection spanning a five mile radius. Any decision to deploy the weapons, in the event of a threat in the airspace, will be taken at a "political level". Personnel operating the equipment will be based at the nearby Army Cadet Centre during London 2012.
The Royal Navy is also preparing for its role in protecting the capital and today brought the largest ship in its fleet, HMS Ocean, to Greenwich for a week of exercises.
The 200 metre long amphibious assault ship, nicknamed as the Mighty O, sailed up the Thames this morning, passing through the Thames Barrier just before eleven. After passing the O2 she was turned around and then pulled towards her mooring at Greenwich Reach.
Lynx helipcopters will be taking part in exercises from HMS Ocean over the weekend and next week exercises will take place on the river.
Greenwich borough residents will have the chance to go on board HMS Ocean on Monday - details available from the council website.
Defence Secretary Philip Hammond said:
"HMS Ocean's arrival in London on the River Thames today completes the build-up of military assets and personnel taking part in Exercise Olympic Guardian over the coming days which will test the role of the Armed Forces in keeping the Games safe and secure.
"The public will expect that we are ready and prepared in the unlikely event that any threat emerges. That is why Typhoon fast jets are stationed at RAF Northolt, ground-based air defences are being tested at sites across London, and helicopters and Royal Marines will be operating from HMS Ocean, the Royal Navy's largest ship, berthed at Greenwich.