The U.S. is sending Marines and additional warships to Middle Eastern waters amid rising tensions with Iran, the military announced Thursday.

Defense Secretary Lloyd Austin ordered the deployment of a Marine expeditionary unit and an amphibious-ready group to the region, citing Iran’s recent attempts to seize ships in the region. A MEU typically includes about 2,000 Marines transported aboard three amphibious warships that can launch helicopters and watercraft.

The announcement comes days after the Pentagon deployed F-35 and F-16 fighter jets, as well as the destroyer USS Thomas Hudner.

“U.S. Central Command is committed to defending freedom of navigation within our area of responsibility which includes some of the most important waterways in the world,” Gen. Michael “Erik” Kurilla, the head of Central Command, said in a statement. “These additional forces provide unique capabilities, which alongside our partners nations in the region, further safeguard the free flow of international commerce and uphold the rules based international order, and deter Iranian destabilizing activities in the region.”

According to the announcement, Iran has attacked, seized or attempted to seize nearly 20 merchant vessels sailing in the area.