Suspected "sabotage operations" on four commercial ships in the Gulf have heightened turmoil in a region already on edge amid an acrimonious standoff between the United States and Iran over Tehran's nuclear programme.
Here's what we know about the alleged attacks:
What happened?
On Sunday, the United Arab Emirates said four commercial ships off the coast of Fujairah, one of the world's largest bunkering hubs, "were subjected to sabotage operations".
There were "no injuries or fatalities on board the vessels" or "spillage of harmful chemicals or fuel", the UAE's Ministry of Foreign Affairs said.
Officials identified the damaged ships as the Saudi oil tankers Al-Marzoqah and Amjad, the Norwegian tanker Andrea Victory, and a UAE bunkering barge, the A Michel.
The Andrea Victory's owners, Thome Group, said an unknown object hit the tanker above the waterline, causing a hole in the hull.
"The ship is not in any danger of sinking," it said.
The Saudi energy minister, Khalid al-Falih, said the attack on the Saudi tankers took place at 6am local time (10:00 GMT) on Sunday and caused "significant damage to the structure of the two vessels".
The UAE published a picture of the damage to the Norwegian-flagged tanker, but did not provide evidence of damage to the Saudi and Emirati ships.
Adding to the tensions, Iran-aligned Houthi rebels in Yemen launched drone attacks on petroleum stations outside the capital Riyadh on Tuesday. The attack caused a fire and minor damage at one pump station, al-Falih said in a statement.
Who's behind the suspected attacks?
The UAE, with US assistance, has launched an investigation into the Fujairah incidents. It has not named a suspect and there has been no claim of responsibility.
Anwar Gargash, UAE minister of state for foreign affairs, called the incidents "deliberate sabotage".
The UAE foreign ministry called the suspected attack "a dangerous development", and al-Falih, the Saudi energy minister, said the "sabotage attacks" were aimed to "undermine the freedom of maritime navigation, and the security of oil supplies to consumers all over the world".
Unnamed US officials, quoted by Reuters and The Associated Press, identified Iran as a prime suspect.
But the officials offered no proof to back the claim.
Why is this significant?
The incident took place against a backdrop of heightened tensions between US and Iran, with Washington deploying aircraft carriers, bombers, and a Patriot missile battery to the Middle East to deter what it called "credible threats" from Tehran.
The military buildup, announced earlier in May, came as the US tightened sanctions it reinstated on Tehran after exiting the 2015 Iran nuclear deal. The landmark pact imposed limits on Tehran's nuclear programme in exchange for sanctions relief.
With the US's "maximum pressure" campaign triggering an economic crisis in Iran, the country's President Hassan Rouhani announced plans to scale back compliance with the nuclear deal unless remaining signatories acted to shield Tehran's economy.
Both countries said they do not want conflict, but bellicose rhetoric is growing on both sides.
A top commander in Iran's Revolutionary Guards Corp called the US aircraft carrier a "target", saying "If [the Americans] make a move, we will hit them in the head".
Meanwhile, the New York Times reported that US President Donald Trump's top aides have updated a military plan that envisions sending as many as 120,000 troops to the Middle East should Iran attack US forces or develop a nuclear weapon.
Trump dismissed the report as "fake news", but said: "If we did that, we'd send a hell of a lot more troops than that". The previous day, he said Iran will "suffer greatly" if they threaten US interests in the Middle East.
Separately, John Abizaid, US ambassador to Saudi Arabia, said Washington should take "reasonable responses short of war" after determining who was responsible for the damage to the ships.
What does Iran say?
Iranian officials have expressed concern, saying the alleged attacks could have been carried out by third parties to stir up conflict between Washington and Tehran.
Hours after the incidents, Abbas Mousavi, spokesman for Iran's foreign ministry, said they were "alarming and regrettable". Calling for the "clarification of the exact dimensions of the incident", he also warned "against plots by ill-wishers to disrupt regional security".
Mohammad Javad Zarif, Iran's foreign minister, also expressed worry on Tuesday, saying: "We had previously predicted that such actions would occur to create tensions in the region."
Heshmatollah Falahatpisheh, a senior Iranian legislator, called for a hotline to be set up between Tehran and Washington to "manage the crisis", while the spokesman for Iran's parliament, Behrouz Nemati, blamed Israel, Tehran's primary rival for the suspected attacks.
An adviser to Rouhani, Hesameddin Ashena, meanwhile accused Trump of moving towards war with Iran, instead of trying to reach an agreement on its nuclear programme.
"You wanted a better deal with Iran. Looks like you are going to get a war instead," he said on Twitter.
But Iran's Supreme Leader Ayatollah Ali Khamenei said there will be no conflict. "Neither we, nor them, is seeking war. They know that it is not to their benefit."
