It occurred to me, as I swooped in to snaffle two Scavenger sites right next to a NJ base, that it would be very interesting if there was a %age chance of those Jerichites being there too.
If you try to scavenge a site that’s too close to another faction, you might stumble over their own scavengers, which could provoke a firefight, affecting your popularity with that faction.
Absolutely no idea how easy or hard that would be to implement, just throwing it out there as an idea.
Both air and ground combat would be great, but will fractions have that kind of AI remains to be seen.
I’d imagine the alien ai would be adaptable enough. And I’m sure the Sim ai is already going to handle most of what would be needed. Could be a good opportunity for some meta game diplomacy… Jericho scavs are already here! Would you like to 1) Leave them be and wish them luck (auto success, gain some rep), 2) Offer to help them clear the site for a cut (some mats, a roll for some rep, maybe a chance of getting screwed by them), or 3) Tell em to take a hike (%chance of success, affected by rep. Succeed, you get all mats, roll for rep staying same or going down. Fail, lose rep, possible firefight).
Could also make it just another resource game, where it allows you to trade faction rep for the supplies there.
Don’t think you’d need to make it as complex (or as artificial as that).
If you scavenged a site that was within, say, 100 (or 1000 depending on how the scale works on the map) miles of a Haven, there would be a %age chance of troops from that Haven being on the scene = the distance of the site from the Haven.
If they’re on the scene, that scavenging site counts as if it belongs to that Haven, and they will fire on any PP squad that opens a crate on that site. The amount of Pop you lose with that faction for scavenging the site would be the same as if you had looted their Haven during a rescue mission.
So the only algorithm the Devs would need to add is the %age chance of Haven Scavengers on-site. The rest is purely up to you.
But your options are like ‘their or our’ thing. JG said that he wanted to give us more options to decide during the mission (do we leave site, do we help clear, and share or not loot, do we attack faction) so maybe Finitethrills idea would work with that.
Hey, if Julian’s already on the case and ahead of us, I’m absolutely fine with that! 
It was about Haven defence. I’m not sure about other types of missions. We will see
If Julian is on the case, he’s automatically a heads of us, as well. 
Definitely get the appeal of trying to not overcomplicate stuff, but I also feel like a binary gtg if no one is there - auto attack if they are is a little too simplified. I mean, if you’re allied with a faction, why on earth would they attack you for scavenging in their territory? You’d be heavily inclined to find compromise on both sides in that case.
I do admit, there may very well be a more elegant way of getting there than what my brain comes up with, though.
We’re in a post-apocalyptic world of finite resources, where alliances are fluid and fuel/ammo/food is a precious, rare commodity. In that scenario, I can see PP muscling-in on an area which another faction sees as ‘its’ territory being a flashpoint for strained relations.
Maybe in the diplomacy screen (assuming there is one), there is an alliance option which allows you to ‘Share Resources’. But unless you’ve come to some specific agreement with another faction, the likelihood is that they are going to see us scavenging resources out from under their noses as an infringement of their territory and act accordingly.
I wondered about this topic, because there definitely will be mission where you will have one faction attacking another. Game will spawn different competing units despite your presence. So I suppose that on scavenge missions it would be also possible.
But on the other hand… Do you imagine scavenge sites being on the other side of the globe? They will all be looted before you will get to them. 
Unless idea is only to spawn faction units on your arrival and that faction would never go that site to scavenge anything on their own.
There’s always a degree of abstraction in any game of this sort. In XCOM, Advent is swarming all over the world, but we only feel their presence/influence in areas directly related to us.
Similarly, in PP, you can assume that factions all over the globe are in a constant state of tension over scavenging and resources which we never see or find, because the game will only ever simulate those areas where we are directly involved.
Still, if I’m a Disciple of Anu under attack by Crabbies, I’m going to take a very dim view of some PP a-hole who instead of coming to help us takes the opportunity instead to steal our stuff, and I think the game should reflect that in some way.