Barack Obama and Angela Merkel are expected to arrive in Newport for the 2014 Nato summit, with staff at the Celtic Manor Resort preparing to cater for 60 world leaders.
An estimated £50 million security operation is in full flow, with almost 10,000 extra police officers drafted in from forces around the country to protect delegates.
Twelve miles of security fencing has been erected around roads in Newport and Cardiff to guard the summit.
The summit kicks off amid growing tensions between Ukraine and Russia, with many looking to Nato to lead a fight back against separatist forces, allegedly armed by Vladimir Putin.
Angus Raffle, 8, says his surprise meeting with the President at Stonehenge was "awesome". His mother says she "squealed like a teenager".
The language has been ramped up at this Nato summit, yet caution appears the order of the day after the mistakes of recent history.
The US President's motorcade pulled up at the school with his black stretch limousine bearing a Welsh flag for the first time in history.