SEOUL — A U.S. soldier was sentenced to five years in prison Tuesday for importing and selling synthetic marijuana in what South Korean authorities have called the largest-ever drug-smuggling ring involving the American military here.

Kim Hwan-su, head judge of the Seoul Central District Court, told the 2nd Infantry Division’s Pvt. Michael Lehmkuhl he had shown no remorse and could have faced up to eight years under court sentencing guidelines. A South Korea prosecutor had recommended 12 years to prove that the South Korean judicial system would not treat military crime lightly.

Lehmkuhl’s best friend and former U.S. Forces Korea soldier Arin Bergquist also was sentenced Tuesday to four years for selling and trafficking Spice and for marijuana possession. Bergquist has said he was discharged in October 2011 and returned to South Korea the following month on a tourist visa to sell the drug.

Bergquist had testified he made several orders for Spice on the internet for delivery to South Korea, then distributed it to Lehmkuhl and others to sell between August 2011 and January 2012. At least one package was delivered via military mail to Camp Casey; others went to the civilian Dongducheon Post Office.

U.S. and South Korean officials have released few details about the case, but at least a half-dozen people — most of whom appeared to be connected to the U.S. military — were named during the two men’s trials.

Kim told Bergquist that while South Korea punishes drug crimes harshly, his sentence was lighter than the seven years recommended by prosecutors because he cooperated fully with authorities during the investigation, leading to the apprehension of “many” suspects.

Both men have seven days to appeal. Lehmkuhl was fined nearly $10,000. Bergquist was ordered to pay more than $11,000.

The smuggling ring has sparked widespread criticism of USFK. One politician condemned the Joint Military Mail Terminal as a “new drug-smuggling route.”

In addition, authorities announced last week that four Camp Casey soldiers were in custody on suspicion of selling Spice. South Korean police said all four were deserters, and at least two were identified in the Lehmkuhl and Bergquist trials as accomplices in their ring.

Police said they were investigating 26 others for manufacturing, selling or using Spice. Thirteen of those were identified as U.S. soldiers, though the military has not confirmed it.

Yoo Kyong Chang contributed to this story.

rowlanda@pstripes.osd.mil