The amphibious transport ship USS Mesa Verde with 550 Marines on board entered the Persian Gulf on Monday.

The amphibious transport ship USS Mesa Verde with 550 Marines on board entered the Persian Gulf on Monday to support possible U.S. action to help Iraq's government combat a violence erupted by the so-called Islamic State of Iraq and the Levant (ISIL) that has overtaken large areas of the country's north, a U.S. defense official said.

U.S. President Barack Obama said he is considering military action, short of putting U.S. troops in Iraq, to help Baghdad's efforts deal with the threat of militant offensive in the north.

The ship’s presence in the region “provides the commander-in-chief additional options to protect American citizens and interests in Iraq, should he choose to use them.” Pentagon Press Secretary Rear Adm. John Kirby said in a statement.

“USS Mesa Verde is capable of conducting a variety of quick reaction and crisis response operations. The ship carries a complement of MV-22 Osprey tilt-rotor aircraft,” he added.

The USS Mesa Verde joins the aircraft carrier USS George H.W. Bush, which moved into the Gulf on Saturday along with the guided-missile cruiser USS Philippine Sea and the guided-missile destroyer USS Truxtun.

President Barack Obama said he considered military action to help the Iraqi government deal with the threat of militant offensive which has already claimed large parts of the country in a surprise lightning operation.