CARDIFF, WALES - AUGUST 26:  Mounted police officers patrol the security fence that has been erected in front of Cardiff Castle ahead of the Nato Summit 2014 that is being held in South Wales next week on August 26, 2014 in Cardiff, Wales. The barriers have been erected in the Welsh capital as a security measure as preparations for the international conference continue at the Celtic Manor Resort in Newport.  (Photo by Matt Cardy/Getty Images)