From the Miami New Times:
Fourteen-year-old Tremaine McMillian didn't threaten police. He didn't attack them. He wasn't armed. All the black teenager did was appear threatening by shooting Miami-Dade police officers a few "dehumanizing stares," and that was apparently enough for the officers to decide to slam him against the ground and put him in a chokehold.
During Memorial Day weekend, McMillian was rough-housing with another teenager on the sand. Police approached the teen on an ATV and told him that wasn't acceptable behavior. They asked him where his parents were, but MicMillian attempted to walk away. The officer jumped off the ATV, and tried to physically restrain the teen. According to CBS Miami, police say the 14-year-old kid gave them "'dehumanizing stares,' clenched his fists and appeared threatening."
McMillian says he was carrying a six-week old puppy at the time and couldn't have been clenching his fists because he was feeding the dog with a bottle. He claims that during the confrontation the dog's front left paw was injured while officer forcibly separated him from the dog.
The officer then forced McMillian to the ground and put him in a choke hold.
.....Miami-Dade Police Detective Alvaro Zabaleta told CBS Miami that McMillian tried to pull away, so that constituted a "threat." The teen was charged with a felony count of resisting arrest with violence and disorderly conduct. Zabaleta claims with a straight face that flailing one's arms and clenching one's fists constitutes a threat, and is not swayed by McMillian's insistence that all he was doing with his arms were carrying a puppy.
"At that point we are not concerned with a puppy," Zabaleta told the station. "We are concerned with the threat to the officer."
Some news video also included at the full link.