The U.S. military destroyed ten Iranian mine-laying naval vessels on Tuesday amid concerns that Iran is preparing to deploy mines in the Strait of Hormuz, President Trump said. Why it matters: A senior U.S. official told Axios the strike on the inactive ships was a preemptive measure that was a result of intelligence about Iran's operational plans.Iran's deployment of mines would create an extreme threat for commercial shipping in the region and prevent any oil from leaving through the Strait. Approximately one-fifth of the world's oil passes through the waterway.What they're saying: Trump threatened Iran in a Truth Social post with "military consequences" at a level "never seen before" if they were to place mines in the Strait."If, on the other hand, they remove what may have been placed, it will be a giant step in the right direction," the president wrote, though he clarified that the U.S. has no reports that mines were placed in the waterway. "Additionally, we are using the same Technology and Missile capabilities deployed against Drug Traffickers to permanently eliminate any boat or ship attempting to mine the Hormuz Strait. They will be dealt with quickly and violently," he added.In a separate post, Trump said ten vessels were destroyed in a strike "with more to follow."Zoom out: CNN reported on Tuesday that Iran has started laying mines in the Strait of Hormuz, but that it was not extensive. "We thought the Iranians were planning to start laying the mines, so we took out many of the ships," the U.S. official told Axios.