警戒线
jǐng​jiè​xiàn

cordon

jǐng​jiè​xiàn cordon
  1. 警戒 jǐng​jiè
    to be on alert
    To guard against; to keep a close watch on; specifically refers to military security measures to prevent surprise attacks or sabotage.
  2. 线 線 xiàn noun
    boundary
    boundary; demarcation line; frontline; verge; brink

jǐng​jiè​xiàn warning line; alert level
  1. 警戒 jǐng​jiè
    to warn
    To admonish or caution someone so they take notice; to alert.
  2. 线 線 xiàn noun
    boundary
    boundary; demarcation line; frontline; verge; brink