Upkeep?

[blanko]

My understanding of this effect from reading prior posts is that lack of upkeep play out as the following:

- If you have not enough gold to pay all upkeep, units begin to desert. The order of desertion is based on morale of troops. Lowest morale troops desert first.

This makes sense, and is a pretty logical way for the game to decision which units desert if, say, only 50% of your gold is available.

My question is, exactly how does this work? Is it a morale check? This makes it possible that you will not have any desertions (granted, that's a longshot). If it's a guaranteed effect - no upkeep, no troops - that's a far bigger deal. Driving other players' income down would result in certain loss of troops and becomes a viable strategy. The second they lose money enough to pay troops, those troops are gone (in a no morale check version of things). This becomes a compelling strategy. Anyone know for sure which it is?