South Korean prosecutors have charged two men with helping a North Korean spy attempt to smuggle used tires into the North that could be used by the military.

The Seoul Central Prosecutor's Office said in a statement dated Friday that the two males were accused of helping the North Korean secret operative from 2014 to 2015, which would violate the South's National Security Law.

The indictments come amid heightened tensions between Seoul and Pyongyang after a series of missile launches by the North this year and the decision by the United States to place a sophisticated anti-missile system in South Korea.