All good questions

I'll add my thoughts, though can't answer all of them. Note that all of this is common knowledge and none from classified sources.

We know now that the three KIAs were from a Georgia reserve Engineer unit stationed out of Fort Moore (formerly Benning). We are relying heavily on our Reserve forces while also running our active Army ragged (as I've mentioned--higher OPTEMPO now than during the Iraq/Afghanistan surges).

I suspect we're in that location (Tower 22 and al Tanf) for several reasons, the primary being intelligence. Additionally, there's still a humanitarian camp nearby (once 100K but now around 7500K), it provides access into Syria, and it impedes a known land logistics corridor. I would guess it is protected by US or contract forces on the gates and C-RAM through the air. Likely artillery support and aerial QRF as well. C-RAM is very effective, but the enemy either got lucky or picked up a good TTP to mirror a friendly drone.

Broadly, we are in Iraq/NE Syria/Jordan as part of the Defeat-ISIS coalition. While an incredibly successful coaltion during the fighting phase, what to do with the refugees (many who are still rabidly ISIS) and prisoners has been much more difficult. There is strong belief that if the coalition leaves the area Turkish/Russian/Syrian/Kurdish fighting will allow ISIS to reconstitute utilizing those refugees and prisoners. So we remain.

I believe Iran is at war with us and has been for some time. Their goal being to expel us from the region (they will always keep an eye on the Sunnis, obviously). The Iranians aren't fools so will push right up to the point our Commander in Chief does something about it...that point varying constantly of course. The current administration isn't the first to allow Iran to kill US Soldiers with no/very little response. Some administrations even rewarded them.

I do not believe we have any appetite for war with Iran. Maybe rightly so. If we did go to war, I would think the only real chance of success would be a broad, slowly built, coalition (ala Gulf War) with a limited political objective (regime change). I don't think we'll get that coalition (unless Iran detonates a nuke or invades somewhere), I don't think we have the internal political will, I don't think we can raise the forces necessary without a draft, and I think we're too broke.

A good portion of our leadership has an affinity for Iran that boggles the mind. A good portion of our leadership believes any meaningful response will mean WWIII. So we'll do something, but probably not much. We're saying so openly now. Our Soldiers will keep dying, probably in greater numbers. We'll watch passively as international shipping lanes are impeded.

As you can tell I am not optimistic, but I've been surprised before (Soleimani).