Nato summit: Protecting President Barack Obama
3 September 2014 Last updated at 15:03 BST
Even with miles of fences, thousands of police officers, helicopters and war ships surrounding the Nato summit, how do you make sure every foreign minister, adviser or head of state gets to the Celtic Manor in Newport safely?
Colonel Stephen Thomas served in the British Army for 36 years and now runs Scimitar security company.
He told BBC Radio Wales' Gareth Lewis that security for President Barack Obama would be particularly tight - and discusses the type of protection around him.