22 June 2014 Last updated at 08:30
Nato's secretary general says the summit in Wales will be "historic" and provide a positive economic impact to Wales.
Anders Fogh Rasmussen said it was the biggest Nato summit and would benefit the nation as a whole.
It was taking place when Russia's "illegal military actions" in Ukraine had "dramatically changed" Europe's security, he said.
Barack Obama will join world leaders at the September summit at Celtic Manor.
Mr Rasmussen told BBC Sunday Politics Wales said: "There's a lot of positive economic spin-off from such an event. [There will be] more than 50 nations and they all bring bigger or smaller delegations so you will see thousands and thousands of people going to Wales.
"This will be an historic summit. We will take very important decisions regarding Nato's future, so for many many years to come this will be remembered as The Wales Summit and this will give a lot of positive public relations effect."
He said Nato had enhanced its policing of air space and had deployed naval vessels to the Baltic and Black Seas following Russia's action in Ukraine.
"We conduct exercises on the ground and we will not hesitate to take further steps if necessary to ensure continued effective defence and protection of our allies.
"We have tried to develop a partnership with Russia, but apparently Russia considers us not a partner but an adversary and of course we have to adapt to that."