A seven-layer security ring will be thrown around the VVIP enclosure with elite Special Protection Group and Secret Services personnel forming a part of the Close Proximity ring, official sources said, adding a radar has been exclusively kept for monitoring air space over the VVIP enclosure. Central Security agencies have brought in their Concealed Anti-Terrorists (CAT) squads to the national capital who form part of teams that carryout surprise checks at hotels, guest houses and vulnerable localities.