Jeremy Binnie, the Middle East and Africa editor at British military magazine Jane's Defence Weekly, said the choice of what was likely a Qiam ballistic missile carried some risk — but it also likely ensured several minutes of warning for the Americans when the attack hit their radars.

"The attack on Saudi Arabia last year used cruise missiles and UAVs, while these were ballistic missiles." he said. "That might have been a deliberate decision to minimize damage, as the Iranians would have known that the ballistic trajectories could be picked up much more easily by radars, providing early warning of the attack"

About the Qiam missile: Binnie said that, according to images released, the missile recovered near Ain al-Assad Air Base was a Qiam, a type that was "recently upgraded with a new re-entry vehicle that has fins so that it can steer itself towards its target"

He said these missiles had been used before to attack ISIS and Kurdish rebels in Iraq, "but their accuracy and reliability was spotty."

"Some missiles failed to reach the target area, while others missed their apparent targets," Binnie said. "If the Iranians were aiming for uninhabited areas at the Iraqi bases, there consequently was still some risk they would accidentally hit a bunker where coalition personnel were sheltering."

Some background: There is a growing belief among some US officials that Iran's missiles intentionally missed areas populated by Americans , multiple Trump administration officials said.

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