Two American men were in Japanese custody Friday on suspicion of violating Japan’s Narcotics Control Law, Japanese officials said.

Babe A. Cole, 25, a civilian worker at Yokosuka Naval Base, and William Jenkins, 27, a former civilian worker, were in Japanese custody after they were arrested Thursday on suspicion of smuggling synthetic narcotic drugs such as Ecstasy (MDMA) tablets and stimulant drugs using the military postal system, a Kanagawa Prefectural Police spokesman said. Their cases were referred Friday to Yokohama District Public Prosecutor’s Office.

The police confiscated a total of 30,000 tablets of MDMA, 20,000 tablets of mixed MDMA and stimulant tablets and 150 grams or about 5 ounces of stimulants, altogether worth a market price of 209 million to 259 million yen (about $1.9 million), police said.

The two men are suspected of mailing drugs from a post office in Canada in early July to a military postal address. The drugs were found during a customs inspection at Narita Airport on July 29 and led to the arrest of the two men, the spokesman said.

Since a large number of drugs was confiscated, police will investigate to see if the case is linked to organized crime.

“The recent arrest of two people associated with the Navy base is a regrettable incident,” a Yokosuka Naval Base spokeswoman said Friday. “We will continue to work closely with Japanese authorities to eliminate the use, possession or introduction of drugs into Japan by anyone associated with the Navy. The Navy has zero-tolerance policy for drug use, abuse or possessions.”