Lamenting Iran's escalation, we should be glad the USS Boxer-led Amphibious Ready Group downed an Iranian drone on Thursday. That drone came within one kilometer of the Boxer before being destroyed.

This U.S. action should not be seen as retaliation for Iran's downing of a U.S. drone in June, but rather as an act of self-defense.

It is justified for two reasons.

First, because Iran uses armed drones as a keystone element of its four-pronged war-fighting strategy for the Persian Gulf and Gulf of Oman (the other three elements being anti-ship missiles, mines, and fast attack boats). Second, because Iran conducted this operation to test U.S. resolve in face of overt threats to American personnel.

While it's not yet clear which type of drone was involved here, it was likely a Shahed 129 type drone. Armable with bombs, and possibly unguided rockets, Iran has previously used this platform to threaten American forces in the region. Regardless, while not nearly as advanced as U.S. military and intelligence drones, Iranian drones can threaten American personnel.

Again, on the available information, this was a justified action. Iran was repeatedly warned to withdraw the drone. The drone closed within 1 kilometer of the Boxer amphibious ready group before being shot down. And remember, Iran's Islamic Revolutionary Guard Corps builds and deploys its drones as a means of lethal threat.

Still, as I warned last month, this kind of Iranian test was always highly likely. The Iranian economy is in free fall and European Union appeasement has failed to restrain the hardliners' anger. Iran would have intended this drone action to threaten American lives in a credible and serious manner. The Boxer amphibious ready group is embarked with the 11th Marine Expeditionary Unit and over 2,000 Marines. So the perceived threat to life was significant, even if unarmed with bombs or missiles, the U.S. commander would have feared the drone might have been armed with explosives and intended to crash into the ship.

Shooting down the drone was the right action to take. Iran knows the United States will defend its personnel with all necessary force. Had the drone been allowed to approach closer, Iran would have been encouraged to escalate even further.