What is the military-industrial complex?

President Dwight. D. Eisenhower famously warned U. S Citizens about the 'military-industrial complex'

It's an informal alliance between a nations military and the private arms industry which supplies it. Basically so that a countries weapons and logistics can be kept secret for as long as possible, and a county has its own weapons. The government doesn't have the capability to make a massive amount of war materials.

Example:

US Air Force uses an F-16 fighter. It was made by General Dynamics. A private company. Transactions like that make the MIC.