Iran’s Revolutionary Guard on Sunday confirmed rumors that they moved up the timing of a large naval drill in the Persian Gulf several days ahead of the Islamic Republic’s planned annual exercises, according to Reuters. State news agency IRNA said the war games were aimed at “confronting possible threats” from enemies.

“This exercise was conducted with the aim of controlling and safeguarding the safety of the international waterway and within the framework of the program of the Guards’ annual military exercises,” Guards spokesman Ramezan Sharif said, according to IRNA.

The U.S. military’s Central Command on Wednesday confirmed it has seen increased Iranian naval activity. The activity extended to the Strait of Hormuz, a strategic waterway for oil shipments the Revolutionary Guards have threatened to block. –Reuters

While Iran didn’t comment on the size of the drill, Haaretz reported on Friday that “more than 100 vessels” would participate, citing a U.S. official.

The U.S. military’s Central Command on Wednesday confirmed it has seen an increase in Iranian naval activity, including in the Strait of Hormuz, a strategic waterway for oil shipments that Iran’s Revolutionary Guards have threatened to block.

“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,” said Navy Captain Bill Urban, the chief spokesman at Central Command, which oversees U.S. forces in the Middle East. Central Command did not update its guidance on Thursday.

A third official said the Iranian naval operations did not appear to be affecting commercial maritime activity. –Haaretz