Iran has begun a major naval exercise in the Persian Gulf, a US defense official told CNN.
According to the official, who is familiar with the latest intelligence, the Iranian Revolutionary Guard Corps launched dozens of small vessels in the first stage of the exercise.
US officials expressed concern over the exercise before it took place, as such exercises are usually conducted later in the year. The official speculated that the exercise was held in response to recent heated rhetoric between Iran's leadership and US President Donald Trump, and that its purpose is to demonstrate Iran's ability to disrupt international shipping routes.
Captain William Urban, chief spokesman for U.S. Central Command, told CNN on Wednesday that "we are aware of the increase in Iranian naval operations within the Arabian Gulf, Strait of Hormuz and Gulf of Oman. We are monitoring it closely, and will continue to work with our partners to ensure freedom of navigation and free flow of commerce in international waterways,".
The Strait of Hormuz is a strategically critical passageway linking the Persian Gulf to the Arabian Sea that is crucial to international shipping and particularly for global energy supplies.
Iran has threatened more than once to close the Strait of Hormuz, with the United States warning Iran in response that any attempt to close the strait would be viewed as a "red line" -- grounds for U.S. military action.
The latest such threat came last month, when the IRGC warned it could block the Strait of Hormuz in the Gulf should the U.S. prevents its oil exports.