ring of steel
Impenetrable defensive perimeter
A ring of steel is a security perimeter of barriers, checkpoints, and surveillance designed to protect an area from attack or unauthorized entry.
The phrase originated with the fortified security zone around London's financial district after IRA bombings in the 1990s: Police established a ring of steel around the summit venue.
Now used for any intensive cordon protecting high-value targets or events.
Encircling line restricting access
- checkpointInspection station on route
- perimeterShape's outer edge length
- bollardTraffic-blocking vertical post
- roadblockObstruction across a road
barricade · security gate · concrete barrier · jersey barrier · boom gate · turnstile · fence · guardrail
Fortified defensive wall
- bastionFortified defensive position
- citadelFortified urban stronghold
- bulwarkDefensive fortification or safeguard
- strongholdFortified place of defense
fortress · battlements · parapet · defensive wall · curtain wall · siege · entrenchment · redoubt
Surveillance camera network
- security camerasMounted recording devices
- monitoringOngoing observation of something
- license plate readersCameras identifying vehicles by registration
- face recognitionIdentifying individuals by countenance
biometrics · sensors · observation · tracking · intelligence · watchfulness · data collection · real-time monitoring
cordon
Encircling line restricting access
- checkpointInspection station on route
- perimeterShape's outer edge length
- bollardTraffic-blocking vertical post
roadblock · barricade · security gate · concrete barrier · jersey barrier · boom gate · turnstile · fence · guardrail · blockade
rampart
Fortified defensive wall
- bastionFortified defensive position
- citadelFortified urban stronghold
- bulwarkDefensive fortification or safeguard
stronghold · fortress · battlements · parapet · defensive wall · curtain wall · siege · entrenchment · redoubt · keep
CCTV
Surveillance camera network
- security camerasMounted recording devices
- monitoringOngoing observation of something
- license plate readersCameras identifying vehicles by registration
face recognition · biometrics · sensors · observation · tracking · intelligence · watchfulness · data collection · real-time monitoring · control room
- encirclementpincer movement, double envelopment, pocket, cordon, investment
ring of steelvulnerability
Openness to harm
weakness · open door · exposed flank · defenselessness · unprotected
ring of steelwelcome mat
Rug at the entrance
open arms · open-door policy · sanctuary · open borders · hospitality
ring of steelopen door policy
Unrestricted visitor welcome stance
welcome mat · vulnerability · exposed flank · open borders · weakness
ring, rings, ringed, ringing, steel, steels, steeled, steeling, steely