Skirmish and sand bags

[7hor]

Hello there

First of all, greetings to all MoW players. I'm pretty new to this game and i started with a friend by doing coop missions in skirmish.

We had a simple question. How do we have new sand bags ? I mean, there is a truck at the beginning wich have many bags but not enough to finish safely the mission.

We didn't see neither the truck in reinforcment .

Is that possible to order new support trucks then ?

Thanks