noun
high alert; severe warning
Used in official or news contexts to describe a state of heightened vigilance or a strong cautionary notice.
台風接近に伴い、気象庁は厳重警戒を呼びかけている。
With the typhoon approaching, the meteorological agency is calling for high alert.
警察はテロの可能性に対して厳重警戒態勢を敷いた。
The police placed themselves on high alert against the possibility of terrorism.
Compound of 厳重 (strict, severe) and 警戒 (vigilance, caution). The exact historical derivation is uncertain, but the word follows standard Sino-Japanese compounding patterns.