[openasocket]

The US probably was able to detect the launch, yes. But would they have assets in place to conduct an intercept in time? Different systems are meant for different targets, and physics put fairly stringent requirements on where an interceptor launcher has to be to protect a specific area. Plus you've got only a few minutes from missile launch to impact. A few minutes to figure out missiles have been launched, confirm it's not a bug or an anomaly, figure out where the target is, get that information from the person monitoring the sensors to command and control plus the missile launch crews, get authority to launch (which depending on the rules of engagement may require going high up the chain of command), get fire control radar tracking the targets (something like SBIR wouldn't be enough, the missile battery needs its own high-quality track), and then launch the interceptor. Also add that people are human beings, and that no one was expecting an eminent strike on Qatar from anyone.

[sudosysgen]

Qatar has a THAAD and Patriot installation, the former assumed to be manned by the US, which can engage these threats. The latter can detect them at a much lower range.

These missiles are not especially fast given the distance they have to cover. They were in the air for 10+ minutes, more than enough time to cross check IR early warning and radar tracks.

[openasocket]

The AN-TPY/2 radar only sees in a 90 degree arc. Given the primary threat in terms of ballistic missiles is from Iran and maybe Yemen (do the Houthis have ballistic missiles that can range Qatar?) they probably weren’t facing in that direction. I’m not sure how SBIR sensors are managed, but I’m assuming Space Force, and I don’t think there is standard automated data sharing of those findings to THAAD or Patriot batteries in the field. So you would probably be looking at someone in Space Force noticing this and sending some sort of priority alert to everyone in the area. Then the battery crews see the alert and turn their radars around, which takes a second. And then you have to think about launch angles for the missiles. If the battery was stationed a couple kilometers from the intended target, fine. But I’m willing to bet they were probably deployed further away, maybe much further away. I believe they are mostly there to protect the US base there. Quick googling estimate indicates maybe 50km, which is closer than I thought but still not close. All of this also assumes that the missile batteries were fully deployed and on ready alert too, which may not have been true.

I should clarify that it is ENTIRELY possible that you are correct. It is entirely possible the US made a choice to not intercept here. My point is that it is also entirely possible that the US didn’t make a choice. I just don’t see enough clear data to tell. I also think that, even if it was a choice, it was probably more of a split-second decision made by lower-level officers on the ground as it happened, rather than a carefully-considered decision made by national security leadership.