Nato leaders will today set out their plans for a new "spearhead" force capable of deploying thousands of troops to take on Russia if required within a few days.
The 28-member alliance is preparing to "pre-position" fuel and ammunition supplies in bases in eastern Europe so they are ready in the event of another crisis.
Airfields and port facilities in the region will also be strengthened.
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.