President Barack Obama has banned the US government from giving certain kinds of military-style equipment to local police forces.
The announcement follows criticism that police were too heavy handed in dealing with protests in Ferguson, Missouri, that turned violent last summer.
It means armoured vehicles on tracks, camouflage uniforms and grenade launchers will no longer be given out.
Tensions between police and African-American communities are strained.
A series of fatal shootings by police have increased mistrust and sparked protests across the US.
In Ferguson and in Baltimore, those protests turned violent, with looting and arson.
But the sight of police dressed in camouflage and riot gear dealing with protests provoked a storm of criticism.
The White House wants police to retain equipment they need to maintain public order.
But a review showed five federal agencies spent $18bn (£11.5bn) on programmes that gave them 92,442 small arms, 44,275 night-vision devices, 5,235 Humvees, 617 mine-resistant vehicles and 616 aircraft.
The study said there was a "substantial risk of misusing or overusing" gear like tracked armoured vehicles, and their presence could undermine trust in police.
What will be banned:
armoured vehicles that run on a tracked system instead of wheels
armed aircraft, ships or vehicles
firearms or ammunition of .50-calibre or higher
grenade launchers
bayonets
camouflage uniforms
And still allowed:
aeroplanes, helicopters and drones
wheeled armoured vehicles
wheeled tactical vehicles, such as Humvees and 5-ton trucks
command and control vehicles
explosives and pyrotechnics
riot helmets, shields and extra-large batons
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