Dae Woong Lee is accused of calling Hackettstown High School back on March 26th.
Officials say the aspiring South Korean solider used an app to mask his true location.
He told a dispatcher he was near the school, armed with an AK-47.
Dae Woong Lee reportedly did it to get back at a female student who he had been talking to online.
He will not be brought to the U.S. to face charges but he does face up to 5 years in prison in South Korea.