A U.S. Navy aircraft carrier and a guided-missile cruiser are steaming toward Yemen from the Persian Gulf, as war there continues to increase tensions in the region.

The USS Theodore Roosevelt, the carrier, and the guided-missile cruiser USS Normandy have made it through the Strait of Hormuz and is moving through the Arabian Sea toward Yemen, Navy officials said. They will join seven other U.S. combat ships and three Navy resupply ships off the coast of Yemen. The move also shifts the Theodore Roosevelt away from Iraq and Syria, where its planes have carried out airstrikes.

[Navy combat ships crowd around Yemen as Saudi-led naval blockade continues]

The Navy sent the additional ships to ensure that vital shipping lanes in the region remain safe and open, accordin to a Pentagon statement. The Navy patrols the region regularly, but is there in force now just as the Saudi Navy has blocked deliveries to Yemen’s ports in an effort to make sure that Houthi rebels in the country cannot re-supply.

Iran, which has been accused of arming the rebels, sent navy vessels of its own into the region this week. The ships are said to be positioned in the Bab al-Mandab strait, the narrow stretch of water between Yemen and Djibouti that connects the Red Sea and the Gulf of Aden.

The U.S. ships are preparing to intercept Iranian ships carrying arms, USA Today reported Monday, citing an anonymous defense official, but Reuters, quoting Army Col. Steve Warren, a Pentagon spokesman, denying that the ships were sent to block arms from Iran. The Navy has long patrolled the waters looking for weapons smugglers, but Lt. Timothy Hawkins, a Navy spokesman, told The Washington Post that U.S. troops have not boarded another ship in the region looking for weapons since April 1.

[How U.S. weapons will play a huge role in Saudi Arabia’s war in Yemen]

The other U.S. combat ships near Yemen are: the destroyers USS Forrest Sherman and USS Winston Churchill; the minesweepers USS Sentry and USS Dextrous; and three amphibious ships carrying about 2,200 Marines, the USS Iwo Jima, the USS New York and the USS Fort McHenry. The USNS Charles Drew, the USNS Laramie and the USNS Arctic also are nearby.