Tenby's relief Tamar lifeboat was launched last night, following several reports of red flares being fired between Pendine and Worms Head.
Braving choppy seas and freezing cold conditions, the lifeboat's volunteer crew carried out extensive searches in the area for around two hours.
They found nothing untoward and, as no one had been reported missing, were stood down and returned to station.
It later transpired that the flares had been dropped by US Hercules aircraft that were on exercise in the area at the time.
The call out was recorded as a false alarm with good intent.
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