Reinforcement
In plural:
Reinforcements are soldiers or police officers who are sent to join an army or group of police to make it stronger.
In variable:
The reinforcement of something is the process of strengthening it.
Reinforcement is relocating forces to any area at risk to strengthen military capabilities as a means of conflict prevention, crisis management, or defense.
Reinforcement. Collins dictionary. Retrieved from https://www.collinsdictionary.com/dictionary/english/reinforcement
NATO. (1997).Chapter 3: Logistic Support of the Alliance’s New Strategy. NATO Logistics handbook. Retrieved from https://www.nato.int/docu/logi-en/1997/lo-318.htm