If you know where they’re launching from, you can equally detect ALBMs or ground launched ones - but given that ALBMs have mobile launch ‘pads’ with thousand+ mile ranges, they’re actually much harder to detect. Hence why we’ve just started rolling out the next gen OPIR this year..

You don't need jets to go over the Red Sea either, Houthi cruise missiles can operate over the Red Sea and then change course to hit their targets.

You do if you want ALBMs… the “A” is pretty important for that acronym.

And cruise missiles are not ballistic missiles. Cruise missiles that tracked up the Red Sea and then crossed 1,200km of Saudi Arabia while heading for Qatar would obviously be detected (and likely shot down) by US and Saudi air defenses.