From Desert Operations Wiki
To be able to build units, you will need the required Buildings and Research. Soldiers will not use any raw materials. The Kerosene is used for the tanks, planes and ships. These units can be produced in the Arms Factory. Defense Systems are always built in the Pentagon.
You can construct more than one of these Units simultaneously . The production times depend on the amount that you already have available. This is different than the construction of the buildings.