The NATO summit is to be one of the biggest security operations ever seen in the UK. That's according to a leading security consultant.
Over 9,500 police officers have been drafted in from 43 different forces.
The operation has taken months of preparation with areas forensically searched and secured.
A wide range of police expertise is being used to cover the summit including; armed police, the military, sniffer dogs and horses.
Part of the security measures has involved putting up 12 miles of nine foot high fencing around the Celtic Manor Resort and areas in Cardiff.
Other preparations have included security tags being placed on drains and manholes close to government buildings.
Meanwhile, 20,000 anti-NATO protesters are expected in Newport during the summit.
There are fears there could be unrest as seen at the previous alliance meeting in Chicago two years ago.
It's a massive operation given that two years ago in Chicago, a NATO conference there, we witnessed major public disorder and there's very likely to be public disorder here in Wales. We are a democratic country and we allow peaceful protests. Whether they will be peaceful or not is a matter to wait for.
The cost of policing the NATO summit is only due to be announced after it's finished.
Top policeman at Nato Summit says stun grenades were destroyed an hour before they were set to explode in path of world leaders.
'Meet the Forces' day was a crowd puller on Sunday as warships open up their decks in Cardiff Bay following Nato summit.
The day began with a spectacular fly-past over Cardiff and Newport by Nato aircraft.