The United States is deploying a third aircraft carrier strike group toward waters near Iran, a U.S. official said, as the war enters its eighth month.

The official said the USS Theodore Roosevelt group left San Diego on Sunday. A Marine expeditionary unit carrying more than 2,000 Marines departed a day later. One published estimate puts the additional personnel involved in the naval deployments at 9,000 to 10,000, including sailors and Marines.

By the end of November, the official expects three carriers and two amphibious landing groups to be positioned near Iran. The official said the buildup would give President Donald Trump more military options if he decides to act.

The deployments come as both sides in the war weigh escalation and diplomatic engagement. They do not, on their own, establish whether further attacks will follow.