[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.

[sudosysgen]

AN/TPY-2 has a 120 degree FoV, and CENTCOM operates them all across the ME, not just in Qatar, but also in Saudi Arabia, the UAE, and in Israel. The likelihood that none of those installations had the ALBMs in range is basically zero.

The chain of actions you're describing would have around 10-15 minutes to be executed.

The likelihood that neither THAAD nor any of the Patriot batteries were sufficiently ready to launch is also basically zero.

THAAD has an engagement range of over 100km, so the battery was undoubtedly in range; and it can cue Qatar's own Patriot batteries so they can launch the missiles; I find it hard to believe there were none in Doha.

So, this would not be a split-second decision - there was quite a bit of time given the proposed trajectory. It's very very unlikely the US didn't have the sensors to see the missiles given the intense concentration of long-range ABM radars in the region.

Is it theoretically possible the US legitimately couldn't do anything? Yes. But the odds are overwhelming that the US knew about the strike with minutes to spare before making a decision, and decided not to protect Qatar.