Iran Used Ballistic Missiles And Cruise Missiles In Its Strike Against U.S.: Here's The Difference

Iranian forces attacked two military bases in Iraq that house U.S. forces by using both ballistic and cruise missiles.

As previously reported, Iran's Revolutionary Guard claimed responsibility for Tuesday night's attack, which was in response to the U.S. drone strike that killed Quds Force commander Qassem Soleimani last week. The Ain al-Asad air base and other areas in Irbil, the capital city in Iraqi Kurdistan, were hit with both types of missiles.

While ballistic and cruise missiles share some similarities, there are key differences in trajectory, detectability and size.

As their name implies, ballistic missiles follow a trajectory that is determined by gravity. According to the Center for Arms Control and Non-Proliferation, ballistic missiles are first powered by a rocket or a series of rockets (launch phase), then arch upward unpowered (midcourse phase) before falling to hit their target (terminal phase). After its fuel has run out, the missile follows an elliptical orbit, which is determined by the velocity and flight angle and the Earth's gravity, according to the Missile Defense Advocacy Alliance (MDAA).

MDAA Director of Government Relations Kyle Shaw told Newsweek that after the launch phase, the target is set and the missile follows only that trajectory. "After that point, it gets set on a certain trajectory where it goes up, hits an apex and then comes down to its desired target, or what its planned target was," he said. "After that launch phase, there's not much movement or capability to re-target it or do something different. It's set on that set trajectory."

The U.S. has four range classifications for ballistic missiles: intercontinental (over 5,500 kilometers), intermediate range (3,000 to 5,000 kilometers), medium range (1,000 to 3,000 kilometers), and short range (up to 1,000 kilometers), according to the Federation of American Scientists. Ballistic missiles used during Tuesday's strike were short range.

Cruise missiles, on the other hand, are propelled by jet engines and use terrain mapping, GPS and inertial guidance to strike, according to the Center for Arms Control and Non-Proliferation. Flights can be preprogrammed, although operators can manually guide the missiles. Cruise missiles also usually stay inside the Earth's atmosphere, making them harder to detect.

Because of their maneuverability and presence inside the atmosphere, cruise missiles "require constant propulsion," Shaw said.

He noted that the biggest differences between the two kinds of missiles are the trajectories and maneuverability. "Ballistic missiles have a set trajectory, whereas cruise missiles can vary and can change in flight."

Shaw also pointed out that ballistic missiles are easier to detect than cruise missiles because they enter the upper atmosphere and space, whereas cruise missiles stay in the atmosphere and can fly closer to the ground.

"With ballistic, since it's traveling more in the upper atmosphere or space even, with all the terrestrial radars, it makes it easier to spot and keep track of. Whereas cruise missiles, they're able to navigate closer to the ground, and that makes it harder for terrestrial sensors to pick up as early as they would be able to with ballistic missiles."

While both missile types can be loaded with similar conventional or nuclear warheads, the sizes can vary. "Cruise missiles might have a lower size of a warhead, as opposed to a ballistic missile might have larger warhead sizes," Shaw said.

Asked if it was common to use both missile types simultaneously, Shaw said it is becoming more common because "it complicates your defense against it. Because you have to then watch for things that are coming at lower trajectories as well as the things that are coming from higher trajectories or a more set trajectory as well."

Trump Iran
Secretary of State Mike Pompeo listens as President Donald Trump speaks about the crisis with Iran in a televised address on January 8. Eric BARADAT / AFP/Getty