Iran on Friday categorically denied US President Donald Trump's claims that Washington brought down an Iranian drone, saying all its craft are accounted for and jesting that American forces may have destroyed their own machine by mistake.
The latest incident in the strategic Strait of Hormuz comes amid soaring tensions between the two foes, with Washington already reeling from Iran shooting down one of its drones last month.
Trump said a US naval vessel downed an Iranian drone Thursday that threatened the ship as it was entering the Strait -- a claim vehemently denied by Tehran.
Iran's armed forces dismissed Trump's assertion as "baseless and delusional" but admitted one of their drones was flying near the US ship.
"All of (Iran's) drones... have safely returned to their bases," said armed forces spokesman Brigadier General Abolfazl Shekarchi.
"There have been no reports of a confrontation with the American USS Boxer" naval vessel, he said, quoted by Tasnim news agency.
On Friday a US official said Washington has "very clear evidence" that it downed the drone but gave no further details.
"It was their drone that came too close to our ship. If you fly too close to our ships, you're going to get shot down," the official said.
The Revolutionary Guards said they would publish photos taken by one of their drones of the USS Boxer.
Images were transmitted to base "before and even after the time Americans claim" the drone was destroyed, they said in a statement on their Sepahnews website.
The Pentagon said the ship "was in international waters" when a drone approached at around 10:00 am (0530 GMT).
Trump said the USS Boxer "took defensive action" against an Iranian aircraft as it was "threatening the safety" of the vessel and its crew.
But Iran's deputy foreign minister Abbas Araghchi quipped that the United States may have actually downed one of its own aircraft.
"I am worried that USS Boxer has shot down their own (drones) by mistake!" Araghchi tweeted.
In June, Iran shot down an American surveillance drone it said was flying in its airspace, a claim denied by Washington.
Trump called off retaliatory strikes at the last minute following the incident.
Iran has refuted US accusations that it was behind a series of recent tanker attacks off the United Arab Emirates coast and the Gulf of Oman.
The tanker troubles further intensified on July 4, when Gibraltar detained an Iranian vessel with the help of British Royal Marines.
Gibraltar's Supreme Court ruled on Friday that the Grace 1 supertanker can be detained for 30 more days.
US officials believed the vessel was destined for Syria to deliver oil, in violation of separate sets of European Union and US sanctions.
Iran branded the seizure "piracy", and a week later London said Iranian boats menaced a British tanker in the Gulf before they were driven off by a Royal Navy frigate.
The incidents have raised fears of a regional conflict involving the US and its allies in the Gulf region, through which nearly a third of the world's oil is transported.
The top commander of Iran's Guards said they were not seeking to "initiate a war" but would respond to hostilities.
"If enemies make a mistake in calculation, our defensive strategy and all our capacities will change to offensive," said General Hossein Salami, quoted by Sepahnews.
His comments came after the Guards said Thursday they had seized a "foreign tanker" believed to be the Panamanian-flagged vessel Riah and its crew.
Iran's Revolutionary Guards accuse the ship of smuggling Iranian fuel.
US Central Command chief Kenneth McKenzie pledged Thursday to work "aggressively" with partners to ensure freedom of navigation in Gulf waters.
But the Guards' deputy chief said the United States will soon realise "it is not in its interest at all to stay in the region".
US forces are under mounting "psychological pressure" in the Gulf, Brigadier-General Ali Fadavi was quoted by Tasnim as saying.
The drone incident comes amid a threatened breakdown of the 2015 Iran nuclear deal, with Washington steadily ratcheting up economically debilitating sanctions on Tehran a year after unilaterally quitting the deal.
Earlier this month, Tehran purposely surpassed the deal's caps on uranium enrichment, aiming to pressure the remaining parties to make good on their promises to support Iran economically.
Iran has repeatedly threatened to close the Strait of Hormuz if Tehran's oil exports are blocked through sanctions.