Why a Phalanx engagement does not identify the incoming threat

Why did Phalanx engage the Red Sea threat rather than another defensive system, and was it a missile or a drone?

The public information does not establish what got through; an automatic Phalanx mount can detect and react before the crew understands the contact.

Several explanations remain open: a missile, a missile mixed with drones, or a drone flying low enough to get through. The engagement alone does not establish which explanation is correct. With Phalanx on automatic, the system can identify a contact and react before the crew realizes what has appeared. Minimal human intervention and very short decision times are central to that defensive role.