Complex sentence: RSTA units also have added light vehicle support in the form of HMMWVs and M3 Bradleys, due to being commissioned as cavalry, whereas the LRS units do not utilize a larger vehicle support element.
Split into simpler sentences: RSTA units also have added light vehicle support in the form of High Mobility Multipurpose Wheeled Vehicles (HMMWV) and M3 Bradleys, due to being commissioned as cavalry. LRS unist in contrast do not utilize a larger vehicle support element.