Why such a low key invasion?

Maybe understanding the failure of Harris' bad cop attitude, they are trying the good cop side?

Maybe Ceres isn't the goal?
It might just be a stepping stone to bigger things. Or the beginnings of a larger Earth presence on Ceres which they'll use to expand their mining operations in an attempt to combat their debt issues?

Earth needs money.  Ceres has it, or at least Earth thinks they do.  Maybe Earth can't afford to send a larger force, or maybe they don't think they need one for a small moon.

Maybe understanding the failure of Harris' bad cop attitude, they are trying the good cop side?

I think it is consistent with the whole EFT storyline, since they sent Gy Gaillard there to ''convince'' Cereans to join to UW, which was indeed a low cost operation, because the UW was looking for new sources of revenues.

Once Guy failed they sent in Butcher Harries Starfleet, the World Conqueror and its escort, if you remember that arc Harris fleet got raped and all his ships seized by Cereans. Which means that the cash hundry UW lost a whole starfleet, which means their cash problems got even worse.

To coumpound the problem the UW having suffered a severe defeat, they must use their remaining starfleet to ''protect'' their other possession, Luna, Mercury or other UW possessions leaving the UW at this point would be a catastrophe.

So to make it short the UW have lost a starfleet to Ceres and can't afford another space battle, so this is why they got their troops in the sneaky way using a commercial flight. Why they have sent so few soldier is for the simple reason that sending more would have rung the alarm bell of Ceres.

So having already lost a starfleet the UW high command wouldn't risk launching a full scale invasion of Ceres without the starfleet needed to make it happen.

Looking at what's been presented thus far, the UW has sent in a roughly company-strength force of light infantry, apparently without even crew-served heavy weapons much less more extended support elements.  These people are clearly getting familiar with the internal populated volumes of Ceres which are open to any tourist or other potential customer.  To what extent are they getting into restricted-access spaces which the Belters don't permit casual visitors to enter?  

Think of Chez Trief, the proprietors of which invite customers into their dining room but not into their kitchen or storage spaces.

The militarily most important portions of Ceres - the "infrastructure," if you will - are not susceptible to this kind of reconnaissance, while the conspicuous insertion of this large number of organized troops could only sound an alarm among the Belters.  

(There's also the fact that such a large number of healthy young people obviously not gainfully employed would present Ceres' entrepreneurs with an enticing wealth of able-bodied economically valuable manpower.  Skilled or unskilled, labor would be the tightest constraint upon wealth-creation in the asteroid belt, meaning that these troops could not wander far from the Hotel de Crillon without being subjected to every kind of recruiting appeal imaginable.)

A real invasion would better have been conducted much more subtly, with people infiltrated in small numbers over a long period, none of them showing any sign of UW service, many seeking work in those parts of the Belter economy such that they are enabled to gain control of key operations when the UW made its move to take over.  

Perhaps this infiltration has already taken place, and the light company pictured in this sequence is merely the equivalent of a ceremonial guard - the obvious iron fist - being deployed in advance of the UW bureaucrats entering Ceres Spaceport to proclaim their regime.

A real invasion would better have been conducted much more subtly, with people infiltrated in small numbers over a long period, none of them showing any sign of UW service, many seeking work in those parts of the Belter economy such that they are enabled to gain control of key operations when the UW made its move to take over.  

I think the subtle invasion attempts already took place, remember that in the beginning the UW sent Guy Gaillards as an emissary to ''convince'' Ceres to join or the classical Hitler game : Surrender already or we will bomb the crap out off you.

This almost worked since Guy was able to get the diplomatic incident the UW wanted and the starfleet showed up to claim UW demand.

Sure maybe in the same way they bough the Hotel maybe the UW troops have bough a very big and important infrastructure on Ceres ... maybe a Fusion Power plant ? The space port itself or the ''Air provider'' and will from there try to stage an incident.

The bottom line is that the UW already have lost a Starfleet and I don't see them risking whatever they have left in another ''Harris Butcher at the gates'' incident, these troops are there for a purpose however.

ETA:
Between the UW lack of starfleet, the lack of central nerve to severe and being vastly outnumbered, I don't see how this will work out

Looking at what's been presented thus far, the UW has sent in a roughly company-strength force of light infantry, apparently without even crew-served heavy weapons much less more extended support elements.

I try to imagine howitzers in Ceres environmental systems and I boggle.

Maybe the UW military thought about it a little bit.

Presumably the first four were there to create disorder, and then the rest of the troops are supposed to restore order. They could behave as police, and when there are more incidents with the new troops then they bring in more and declare martial law.

Presumably they believe that there would be a lot of Belters who would welcome police protection, and this would give them a start at contacting those

Presumably they believe that there would be a lot of Belters who would welcome police protection

Thats the heart of it I think.  Earth leadership must be a strange mixture of ingnorance and hatefullness.

I wonder about the timing, the 4 show up, time passes, the troops show up. They were in transit for some amount of time. Once in flight they keep going. Messages move instantaneously over the Tanglenet, ships do not. Maybe this "phony war" to borrow a phrase, is a plan B.

Since UW is able to buy property they could have given the troops beer money, but didn't. So no commercial interaction wanted.

As to how they arrived, in Steinbeck's The Moon is Down, the unnamed invaders came by the civilian ferry like every one else.  As best as I recall anyway. It's a good little book folks, Hitler hated it and that has to be good.

Was it an inspiration in any way?

I wonder about the timing, the 4 show up, time passes, the troops show up. They were in transit for some amount of time. Once in flight they keep going. Messages move instantaneously over the Tanglenet, ships do not. Maybe this "phony war" to borrow a phrase, is a plan B.

In think you are about that it reminds me of Irving Hitler's War, were Hitler had called off the invasion of Poland for the negotiation even tough his subversive troops were already behind enemy lines.

The 4 failed to get the ''UW soldiers beaten by Cereans mob'' and ''UW officer gang raped by anarchist mob'' headlines, but the troops in transit were already on their way and recalling would have just blown up the plan.

When they find that there is no onw to prevent it , perhaps they will open an ice mine.

If all they want is money they could do exactly the same thing that the origional settlers did to gather valuable minerals with greater ease because they have a settlement to start from.

They can also operate a hotel at a profit, perhaps buy out other businesses as they become availible.

If they are willing to take the time they would be able to do everything the origional population ever did to make money and they would be able to send plenty of new people to do it.

I recall in the movie "Bravehart" the King of Englands comment that the cheif problem with Scotland was that it is full of Scots. Fortunately it was not hard to outnumber them.

If this was the plan, (and I have no knoledge of the plot so this is the kind of guess anyone can guess)I would expect that the answer would be the Natives ability to recruit the soldiers by seduceing them into their society, then the commander would have a problem similur to Captain Bligh 's problem when the Bounty stayed too long in Tahiti.

Heavy weapons, suits and such could be there already in crates labeled machinery. No inspectors, who knows.

And the sign says, short haired army looking people need not apply, as you were, make that read Danger, High Voltage, Keep Out, Especially Invaders. Works for me.

I really like Ed's passion about current events, he has seen this before and he is not a bit happy.

And Then There Were None, the ancestor of all seduce the invaders stories.
http://www.abelard.org/e-f-russell.php

When they find that there is no onw to prevent it , perhaps they will open an ice mine.

If all they want is money they could do exactly the same thing that the origional settlers did to gather valuable minerals with greater ease because they have a settlement to start from.

Obviously, the UW wants more than money--they want the power of controlling people.  Their previous defeat on Ceres makes them look bad, and undermines confidence in the UW's ability to keep things under control.

Yes, they could make money, but it's doubtful that they could make enough money to significantly dent the UW budget, especially if they are inflating the currency.

Besides, government and military personnel are not used to thinking in entreprenurial terms, and would probably not run a business very well.

Think of Chez Trief, the proprietors of which invite customers into their dining room but not into their kitchen or storage spaces.

New guy in town: "I'm throwing a big party next month, money is no object, and I think you should cater.  May I see your kitchens?"
Owner of Chez Trief: "Follow me.  Would you also like to see our storage spaces?"

The militarily most important portions of Ceres - the "infrastructure," if you will - are not susceptible to this kind of reconnaissance,

Surface buildings, their connecting tubes, and their radiation are easily detectable from space.  No secrets there.

I've got the impression that Tanglenet doesn't need large-scale infrastructure.

I would expect most good-sized human-occupied buildings (or major sections of building complexes) to have their own power and air supplies, with backup.  (Not for defense, just intelligent engineering in a hostile environment.)  Depending on the economics, they might usually get their power and/or air from larger centralized sources, but wouldn't depend on them for critical needs.

What sort of infrastructure subject to reconnaissance do you have in mind?

A real invasion would better have been conducted much more subtly, with people infiltrated in small numbers over a long period, none of them showing any sign of UW service, many seeking work in those parts of the Belter economy such that they are enabled to gain control of key operations when the UW made its move to take over.

Perhaps this infiltration has already taken place, and the light company pictured in this sequence is merely the equivalent of a ceremonial guard - the obvious iron fist - being deployed in advance of the UW bureaucrats entering Ceres Spaceport to proclaim their regime.

If a significant number of new people had arrived in the recent past, I'd expect widespread speculative gossip.  So, I expect that the invasion force will be the four 'canaries', the soldiers we've already seen, and any more that arrive later (which could be quite a few).

Since the arc is titled "The Christmas War" and it's only a few days until Christmas, whatever happens should happen soon.

Could Earth's government be planning to attack while King Reginald is undergoing treatment on Mars?  They might think that the government would be paralyzed and defense would collapse.  (Killing him wouldn't work as well, as a successor could take over.)  Capturing the "palace" and a few other key points might be their entire plan (not unlike the TFG/AU invasion of Somalia).