'This is the Story of Power in this Country'

"The quiet militarization of police departments began in 1990, when Congress passed the National Defense Authorization Act, a provision of which — known as the 1033 program — allowed the Secretary of Defense to 'transfer to Federal and State agencies personal property of the Department of Defense, including small arms and ammunition.'

"In 1996, during the peak of the War on Drugs, Congress expanded the program and incentivized active use of the equipment, making it free for recipient agencies and simultaneously requiring them to use it within a year. The expansion of the 1033 program also required agencies to give preference to transferring equipment for 'counterdrug and counterterrorism activities.' And it hasn’t stopped there.

The rest of the story:
Ferguson, Institutionalized Racism and the Militarization of Police: 'They're willing to sacrifice the lives of the community members based on the actions of a few' by Nadia Prupis (Common Dreams)