Supply lines are fragile things, but an absolute must have. That being said, there would need to be signficant resources allocated to the utilization and protection of those supply lines. One little step, and it can come crashing down.
Individuals added for protection in armored vehicles can't be expected to stay in there infinitely. They will have to refuel (the persons and the equipment) and appropriate rest breaks and/or changes in personnel allowed. Now spread those lines out over thousands of miles, and hundreds of stops to collect supplies and ultimately deliver supplies, and you have a whole lot of opportunities in the making.
Similarly, it is also why it could be preferential to seriously wound the enemy instead of outright killing them. It requires resources to remove them, provide them treatment; which means less in the field. Likewise, if they just left the wounded to die, it would eventually have a demoralizing effect on those wondering if they will be left to die as well.
The politicians that send out the SWAT teams will be the villains.