A U.S. official says military experts believe explosives blew holes in four ships off the coast of the United Arab Emirates Sunday, and suspects Iran may be involved but they have no proof.

Two of the oil tankers belong to Saudi Arabia, which says the ships suffered “significant damage” in what it and the UAE calls sabotage. 

Saudi Oil Minister Khalid al-Falih said the attack was meant to undermine “the security of oil supplies to consumers all over the world.”

​One of the others was a Norwegian-flagged vessel and fourth belongs to the UAE. No one was hurt and no oil spilled from the damaged ships.

U.S. officials have so far given no details on exactly what happened to the ships and have no proof of who was responsible.

But one official says Washington suspects Iran.

“This is what Iran does… the sort of thing you could see Iran doing… it fits their modus operandi,” the official told Reuters.

Iranian Foreign Ministry spokesman Abbas Mousavi said Monday the attacks “are alarming and regrettable.” He called for “further investigation,” warning the incident may have been “part of a plot by parties trying to create havoc in the region.”

The U.S. official says Iran is “trying to muddy the waters” with such comments. 

The U.S. Maritime Administration warned last week of what it called the “increased possibility that Iran and/or its regional proxies could take action against U.S. and partner interests … by targeting commercial vessels, including oil tankers or U.S. military vessels.”

Asked at the White House about the incident, President Donald Trump responded: “We’ll see what happens with Iran. If they do anything, it will be a very bad mistake.”

The Arab League, the Gulf Cooperation Council, Egypt, Kuwait, Bahrain and Jordan all condemned the attack.