At first glance, it was possible to miss the puncture at the waterline of the Andrea Victory, a 600-foot Norwegian oil tanker anchored off the United Arab Emirates.
The damage appeared relatively minor, and no one has been officially blamed.
And yet, there are growing fears that this mysterious, obscure incident could become a catalyst — accidental or otherwise — that inflames the already knife-edge tensions between the United States and Iran.
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It also warned that there was an increased risk of Iran "targeting commercial vessels, including oil tankers, or U.S. military vessels" in the region.
On Monday, Trump stopped short of blaming the country directly for this incident.
"We'll see what happens with Iran. If they do anything, it will be a very bad mistake," he told reporters. "If they do anything, they will suffer greatly."
Separately, Saudi Arabia on Tuesday blamed Yemeni rebels aligned with Iran for launching explosives-laden drones at oil facilities. State oil company Aramco shut down pumping on one of its pipelines and oil prices rose sharply, but no injuries or deaths were reported.
The rising temperature has prompted some politicians and experts in Europe to urge calm — particularly when so much seems unclear about who carried out the attack.
"We are very worried about the risk of a conflict happening by accident," British Foreign Secretary Jeremy Hunt said at a summit in Brussels with U.S. Secretary of State Mike Pompeo.
Hunt said he was concerned about "an escalation that is unintended really on either side but ends with some kind of conflict." He called for "a period of calm to make sure that everyone understands what the other side is thinking."
It was the latest sign of daylight between the U.S. and its European allies on their policies regarding Iran. While the European Union shares some of Washington's concerns about the Islamic republic, the 28-country bloc still backs the nuclear deal and wants to salvage it.
What worries some experts in Europe is the bellicose rhetoric being exchanged between the U.S. and Iran.
Never mind who was behind Sunday's attack, it is the mere uncertainty surrounding it, combined with the warlike words exchanged by both sides, that escalates the risk for some misunderstanding leading to war, so this theory goes.
"Regardless of whether these ships got hit by Iranians or not, the Americans and the Iranians have gotten themselves into this cycle where neither seems to be able to back down from making belligerent statements," according to Michael Stephens, a research fellow at the Royal United Services Institute, a London-based think tank.
The tough talk employed by Trump, Pompeo and national security adviser John Bolton carries significant and perhaps unintended and unforeseen risks, Stephens said.
"If that's what drives the Iranians to the negotiating table, then it's a successful tactic," he said. "But it really is playing with fire, and all it takes is for one thing to go wrong because the Middle East is a tinderbox."
The crux of all this is the debilitated Iran nuclear deal.
Iranian President Hassan Rouhani warned last week that his country might restart enrichment of higher grade nuclear fuel if other nations do not help get around the restrictions imposed by Trump after he pulled out of the agreement.
"The crunch point is whether Iran decides to pull back from its commitments on the nuclear deal," Stephens said. "If it does that, then I think all bets are off really."
For its part, Iran has denied all involvement in Sunday's maritime sabotage. While information is scant, some analysts believe the country would be reluctant to sanction such a direct assault and risk triggering a war it would surely lose.
Iran's foreign ministry echoed the conspiracy theories bouncing around some corners of the internet, suggesting it may have been some kind of false-flag operation staged as a convenient pretext to war.
Spokesman Abbas Mousavi spoke of a vague "conspiracy orchestrated by ill-wishers" and "adventurism by foreigners," according to the state-run IRNA news agency.