More On Iran

Selva's comments come one day after the Pentagon ordered 1,000 more troops to the region as tensio continue to rise.

The Pentagon also released more still photos of the alleged Iranian attack on a tanker in the Gulf.

A B-52H and fighters from the Lincoln Strike Group passed over the carrier recently in a show of force to Iran.

Iran and an Iranian proxy group fired surface-to-air missiles at U.S. drones in recent days, the official said.

The head of Iran's fast-boat navy maintains that the U.S. is all bluff.

Limpet mines have also been used in other recent attacks attributed to Iran.

Joint Chiefs Chairman Gen. Joseph Dunford said the U.S. faces a new and varied threat from Iran.

Shanahan announced the move Friday to "safeguard U.S. forces given the ongoing threat posed by Iranian forces."

In targeting the IRGC, the administration is zeroing in on the organization most responsible for maintaining the regime.

Mattis emphasized diplomacy and cooperation as critical to beating back the tide of radical terrorism around the world.