The United Arab Emirates reported on Sunday that four commercial vessels including two Saudi oil tankers had been sabotaged offshore from the UAE emirate of Fujairah just outside the Strait of Hormuz.
A US official familiar with American intelligence said Iran was a leading candidate for having carried out the attacks but the United States does not have conclusive proof. The U.S. Navy's 5th Fleet, which patrols the Mideast and operates from a base in Fujairah, has repeatedly declined to comment.
Iran rejects the allegation of Iranian involvement and Iranian Foreign Minister Mohammad Javad Zarif said that "extremist individuals" in the us government were pursuing unsafe policies.
"As tensions continue to escalate, further actions need to be weighed against Iran's sophisticated, intricate, and nimble regional strategy", private intelligence firm The Soufan Group wrote in a Tuesday analysis note.
The assaults marked the latest incidents challenging Mideast security after the alleged sabotage of oil tankers off the coast of the United Arab Emirates earlier this week amid heightened tensions between the US and Iran.
Saudi Arabia says it was forced to shut down a key pipeline connecting the country's oil-rich east to a Red Sea port on Tuesday after two pumping stations came under attack by armed drones, with the country's oil chief blaming Iran for the incident. A boom surrounded the Emirati oil tanker A. Michel, indicating the possibility of an oil leak. So the question comes, how is Iran going to push back?
Some analysts have said that with the growing presence of USA military hardware and troops in the Persian Gulf, even the slightest misstep could set off a serious conflict in the region.
A Reuters witness said divers were inspecting the ships.
Saudi Arabia offered no immediate confirmation of the report. It added that Saudi Aramco's oil and gas supplies have not been affected by the attack.
The attack did not lead to any casualties or an oil spill but caused significant damage to the structures of the two vessels, said the statement carried on state news agency SPA.
Oil prices initially spiked in response to news of the attacks, but were largely flat in trading on Tuesday.
Iran has called for an investigation into what it called an "alarming" incident, while a senior member of Iran's parliament blamed Israel on Tuesday for the attacks on the ships, for which no one has yet claimed responsibility.
He warned against "foreign seditious plots to upset the region's security and stability".
Nearly all the oil exports of Saudi Arabia, Iraq, UAE, Kuwait, Qatar and Iran itself, at least 15 million barrels per day, are shipped through the Strait of Hormuz.
United States President Donald Trump warned Iran against a military provocation and said the country "will suffer greatly" if hostilities break out with the US.
The New York Times reported late on Monday that the Pentagon had developed an "updated military plan" that would involve sending as much as 120,000 troops to the Middle East if Iran were to attack U.S. forces or accelerate its nuclear weapons program.
Last week Iran had threatened that it would resume enriching uranium at higher levels within two months if terms for a new deal are not agreed on by then.
European Union leaders are scrambling to save the 2015 nuclear deal, which the United States pulled out of a year ago.
Secretary of State Mike Pompeo traveled to Russian Federation on Tuesday for talks that are reported to focus on Iran - an ally of Russia's in many Middle East conflicts - as well as arms control. How are they going to show the United States that if you keep pressing us, we can respond? "Our aim is not war", Pompeo told CNBC in an interview.
Underlining the regional risk, the general-secretary of the six-nation Gulf Cooperation Council described the incident as a "serious escalation".
"Such irresponsible acts will increase tension and conflicts in the region and expose its peoples to great danger", Abdullatif bin Rashid al-Zayani said.
"The kingdom condemns this cowardly attack".
"Since early May, there is an increased possibility that Iran and/or its regional proxies could take action against USA and partner interests, including oil production infrastructure, after recently threatening to close the Strait of Hormuz", the warning read.
The agency on Sunday issued a new warning to sailors about the alleged sabotage and urged shippers to exercise caution in the area for the next week.
As a precaution, the Pentagon has moved an aircraft carrier, B-52 bombers, a Patriot missile interceptor battery and more naval firepower to the Gulf region.