army
arrest
background
barb
barbed
barbwire
barrier
blue
border
boundary
closed
crime
danger
dangerous
design
deterrent
farm
fence
forces
freedom
gate
guard
iron
isolated
jail
keep
metal
military
prevent
prison
private
property
protection
razor
safety
secure
security
sharp
silhouette
sky
spike
steel
stop
symbol
system
torture
violence
war
warning
wire