SEOUL — A U.S. soldier has been sentenced to 2½ years in prison for smuggling into South Korea more than five pounds of an active ingredient found in synthetic marijuana.

Pvt. Curtis Briggs, 20, of the 498th Combat Sustainment Support Battalion based at Camp Carroll, was also given three years of probation Wednesday, court officials said.

According to a Daegu District Court judge, an unknown accomplice shipped a box containing five zip-lock bags filled with AM-2201 — a component of many synthetic marijuanas — to Briggs from a U.S. Post Office in Cleveland, Miss. The box arrived at Incheon International Airport and passed through the initial customs screening undetected, though drug-sniffing dogs later alerted airport officials about suspicious contents.

Authorities have said the case has no apparent link to the recent discovery of a drug-smuggling ring that involved at least half a dozen people — most of whom are believed to be former or current U.S. Forces Korea soldiers or to have some connection to the military — who participated in ordering or selling synthetic marijuana.