A drone strike on Egypt's Mediterranean port of Damietta could be a warning that U.S. interests across the Middle East remain vulnerable as fighting between the United States and Iran continues, analysts said.

No group has claimed responsibility for Wednesday's attack, which hit the U.S.-owned and operated Energos Winter floating gas storage vessel. Egypt has not assigned blame, while Yemen's Houthi rebels denied involvement.

The strike, the first on Egyptian territory since the U.S.-Iran war began, also marked the conflict's expansion beyond the Red Sea into the Mediterranean.

Analysts said the attack may have been intended to pressure Egypt, which has maintained diplomatic ties with both Washington and Tehran and has served as a key intermediary in regional negotiations.

"The attack may have been calibrated to damage a United States-linked asset without killing Egyptians," King's College London professor Andreas Krieg told AFP.

Krieg said the strike was intended "to show that United States assets are vulnerable beyond the Gulf."

"For Egypt, this is a warning that neutrality does not guarantee immunity," he added.

Royal United Services Institute analyst H.A. Hellyer said the distance involved made it unlikely Iran launched the drone directly from its own territory, though he said Iranian-aligned groups could have carried out the attack.

He warned such an attack would represent a major escalation.

"Cairo and others would see an attack by any Iranian-aligned group on Egyptian territory as a formidable escalation, and that won't go down well for the medium-to-long term at all for Tehran," Hellyer told AFP.

The attack has also raised concerns over shipping through the Mediterranean, which has become a key alternative route as vessels avoid the Strait of Hormuz and the Red Sea because of the regional conflict.

Egyptian authorities said Damietta port remains operational and that maritime traffic through the area continues normally.