General Steele will send you a Care Package for FREE containing a number of Reinforcements and Airstrikes. These can be collected by pressing the Comms button on the lower left-hand corner(shown as an envelope symbol)
In order to take advantage of the FREE Care Packages, you must be signed into Facebook.
To get more you can get more in game using Gems or you can connect with Facebook and share Care Packages with your friends, each Care Package contains free Reinforcements/Airstrikes
If you run out of either Reinforcements or Airstrikes during playing a level, you can purchase more using Gems