Washington (AFP) - From high-powered assault rifles to camouflage-clad police officers perched on top of heavily armored vehicles: the violence gripping the Missouri town of Ferguson has highlighted a growing militarization of US law enforcement seen by many as disproportionate.

Since the death on Saturday of unarmed black teenager Michael Brown, shot dead by a police officer, Ferguson has exploded into a seething morass of urban riots.

But it is the police response to the unrest which has unsettled many across America.

While police have used traditional crowd control tools such as teargas in Ferguson, they have also deployed body-armored officers toting M4 assault rifles and stun grenades.

One image of a police officer wearing fatigues and carrying a sniper's rifle while sitting on an armored car quickly went viral.

The detention of journalists reporting on the violence on Wednesday has also angered many, with the Organization for Security and Cooperation in Europe (OSCE) denouncing the "intimidation" of reporters from the region.

President Barack Obama sought to cool the roiling fury on Thursday, stating that while there was "never an excuse" for violence against police, neither could "excessive force" by officers be justified.

Nathan Bethea, an ex-infantry captain in the US Army who completed a 13-month tour of duty in Afghanistan, said he had been appalled by police tactics witnessed in Ferguson.

"I retweeted a picture of a guy they had pinned a laser on -- a kid who was not even wearing a shirt and much less a weapon," Bethea said.

"Using incendiary grenades, flash bang grenades, tear gas. It seems completely disproportionate to the threat.





- 'America, not Fallujah' -





"It's America, not even a huge city and you see them acting like it's the invasion of Fallujah in 2004," he added, referring to the bloody battle for the Iraqi city a decade ago.

Many see the scenes in Ferguson as the logical consequence of the "1033 program". Launched in the 1990s, the scheme allows the Pentagon to recycle military grade equipment to law enforcement across the United States. The police in Ferguson are one of 8,000 local forces which have benefited from the scheme.

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"Since that time local police have been stockpiling arsenals of weapons that are built for combat," explains Kara Dansky, of the American Civil Liberties Union (ACLU).

In a study titled "War Comes Home" published in June, Dansky denounced the "excessive militarization" of American police forces.

The increasingly frequent use of Special Weapons and Tactics (SWAT) teams was often hard to justify, Dansky said.

"For our investigation we looked at over 800 examples of SWAT raids that took place over the course of two years and we found that only seven percent of those were for real emergency situations, close to 80 percent were raids on people's homes often to look for small amounts of drugs," Dansky told AFP.





- Escalating risks -





Often, Dansky said, the tactical approach proved to be counter-productive.

"We saw over and over again that the unnecessary use of paramilitary equipment and tactics escalates the risk of violence and puts people at risk," Dansky said.

So why do so many American police forces believe it is necessary to arm their officers to the teeth in certain situations?

Larry Amerson, sheriff in rural Calhoun county in Alabama, said his force recently took possession of an MRAP armored vehicle designed to withstand a blast from roadside bombs.

For Amerson, the hardware is a welcome addition.

"In 2000 I was sheriff and we had an incident where we had to deal with a mentally deranged man," he explained.

"In that incident he shot three law enforcement officers, we could not get personnel to where the officers were because the man was still armed and the shooting ongoing.

"We had no way to get close to rescue those injured people because we couldn't protect ourselves. So, that piece of equipment gives us the capability to move in dangerous environments in a safe manner."

Many remain unconvinced. Rand Paul, the Republican senator for Kentucky seen as a potential candidate for the 2016 presidential election, believes the militarization of US police forces needs to stop.

"There is a legitimate role for the police to keep the peace, but there should be a difference between a police response and a military response," he argued in a commentary in Time magazine.

"The images and scenes we continue to see in Ferguson resemble war more than traditional police action."

Paul claimed the federal government had "incentivized the militarization of local police precincts" by helping local government "build what are essentially small armies."

"That goes far beyond what most of Americans think of as law enforcement," Paul said.