A US official says an American military team's initial assessment is that Iranian or Iranian-backed proxies used explosives to blow large holes in four ships anchored off the coast of the United Arab Emirates.
The official claims each ship has a 1.5-to-3m hole in it, near or just below the water line.
The US military team assesses that the holes were caused by explosive charges. The UAE asked the US to help investigate the damage, which Gulf officials have characterised as sabotage.
America's Government has warned ships that "Iran or its proxies" could be targeting maritime traffic in the region, and the US has moved additional ships and aircraft into the region.
Two Saudi oil tankers and a Norwegian-flagged vessel were said to be damaged.