Yoel Oberlander, 36, pleaded guilty in U.S. District Court in Newark in March to assault with the intent to stalk.
He must serve out the entire sentence: There's no parole in the federal prison system.
Oberlander was sitting next to the victim and her mother on a May 29, 2016 El Al flight from Tel Aviv to Newark Liberty International Airport, authorities said.
During the flight, he admitted Wednesday, he "touched [the victim] in the area of her chest, upper thigh, and hand without her consent, and that he did so with the intent to harass and intimidate her," Acting U.S. Attorney William E. Fitzpatrick said.
In addition to the prison term, U.S. District Judge Esther Salas sentenced Oberlander to three years of supervised release.
Records show Oberlander pleaded guilty in New York in 2002 to sexually assaulting an 11-year-old girl. He was sentenced to six months probation and moved to Monsey in 2005, records show.
Oberlander also was arrested on trespassing charges in 2012 after police said he entered a boys' dormitory at a Catskills sleep-away camp for Orthodox boys 13 and 14 years old.
Fitzpatrick credited special agents of the FBI, along with Port Authority police. Assistant U.S. Attorneys Melissa M. Wangenheim and Joyce M. Malliet of Fitzpatrick's Criminal Division in Newark handled the case.
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