Two Saudi oil tankers have suffered “significant damage” in what the kingdom says it believes were acts of sabotage. The incident, which officials said could threaten global oil supplies, came three days after the U.S. Maritime Administration issued a warning that “Iran or its proxies” were planning to target commercial vessels and oil-production infrastructure. The state-run Saudi Press Agency reported Monday that there was “significant damage to the structures of the two vessels,” but gave no details on casualties or how much oil was spilled. The agency reported one of the two vessels was on its way to be loaded with Saudi crude oil for customers in the U.S. Iran’s foreign ministry called for clarification about what exactly happened with the Saudi tankers, with spokesman Abbas Mousavi warning against any “conspiracy orchestrated by ill-wishers” and “adventurism by foreigners” to undermine stability and security.