Bahrain activated its civil defense sirens early Friday, warning residents to shelter from incoming fire.
The alert came shortly after the US military confirmed it had completed its 13th consecutive night of strikes against targets in Iran.
This development signals a significant widening of the conflict zone, moving beyond direct military exchanges to include civilian infrastructure alerts in neighboring Gulf states.
The escalation raises immediate concerns for global energy markets.
The Strait of Hormuz, through which a substantial portion of the world's oil supply passes, remains a critical chokepoint.
Any further disruption to shipping lanes or damage to infrastructure in Bahrain or nearby Kuwait could trigger a sharp spike in Brent crude prices and freight rates.
Markets are likely to price in a higher risk premium for Middle Eastern oil as the conflict intensifies.
This latest flare-up follows a period of intense diplomatic and military maneuvering.