Define monstrous. Spirits can certainly qualify, and the UCAS will have had to deal with them on a semi-regular basis. Also, there were several UN investigators that went and got themselves killed in Asamando. It seems reasonable to me that there may have been a UCAS response of some sort (even if it involved special forces and proxy forces like shadowrunners). Also, don't forget that Fort Lewis is in Seattle - one of the most monstrous things that they would have had to deal with was the Renraku Arcology. But they'd also have had to deal with any number of threats involving their paracritters in the zoo, shadowrunners throughout, and international defense from the various countries and interests in and around Seattle. Chicago is an obvious choice, as the bugs had to be dealt with by a lot more than just Eagle Security or Lone Star. Additionally, it seems reasonable to me that the UCAS military would likely be working with Ares Firewatch teams. This means that there may have been a presence in space. Ares built a small station with the express purpose of trying to find the insect spirit home plane. No reports on if they were successful or not, but I think not.
