The phrase "a ring of security" is correct and usable in written English.
It can be used to describe a protective barrier or a system of safeguards that encircles or surrounds something to ensure safety.
Example: "The company implemented a ring of security around its data centers to prevent unauthorized access."
Alternatives: "a security perimeter" or "a security barrier".
They formed a ring of security that tightened each day.
Last month the huge Mangueira favela was "pacified", creating a ring of security around the Maracanã stadium.
The players were surrounded by a ring of security guards in the centre circle in case of a pitch invasion.
In Afghanistan, however, few foreign governments want to deal with the Taliban, preferring a "ring of security" around Afghanistan to contain the problem.
Mr. Wardak, who had overall responsibility for the parade and whose troops provided a ring of security around the capital, also admitted that the security forces had failed.
Worshippers entered the churches for Christmas Eve Mass in a ring of security.
The new government of President Mohamed Abdullahi Mohamed — a dual Somali-American national known by his nickname Farmajo — has sought to impose a "ring of steel" security strategy in Mogadishu since his election, in February.
Even though she was protected by a ring of federal security guards during that week, the harassment was too much.
Organisers have insisted that the teams were "working very well together", but the source said relations were now so strained that an extra ring of security had been put around Boyle's trailer within the Olympic stadium.
About 100,000 security personnel have been deployed around the country, with 40,000 Afghan police officers guarding the polling stations and towns, 20,000 newly trained Afghan National Army troops providing an outer ring of security, and with about 18,000 coalition troops, led by an American force, trying to keep an eye on all of it.
