Attacks on Jews in New York more than trebled last year, according to figures released by the Anti-Defamation League.
There were 22 assaults on Jewish New Yorkers in 2013, compared to just six in the previous 12 months.
The ADL said it could not explain the significant rise, but it is thought the "knockout game" trend was partly responsible.
As part of the knockout stunt, an unsuspecting victim is punched by an attacker who films the assault and then posts footage on social media sites.
