WASHINGTON, May 14 (Xinhua) -- A U.S. sailor stationed in Japan is under investigation for allegedly smuggling narcotic drugs into the country, U.S. media reported on Monday.

The U.S. Navy and Naval Criminal Investigative Service is cooperating with Japanese authorities to investigate "a U.S. service member's alleged involvement in drug distribution," said Stars and Stripes, a multimedia news organization authorized by the U.S. Department of Defense to provide news and information to the U.S. military-related community.

The Navy takes illegal drug use "very seriously" and has a "zero tolerance policy" for drug use, possession and distribution, it quoted Jim O'Donnell, a spokesman for Yokosuka Navy Base in Japan, as saying.

According to Japanese police papers submitted to prosecutors, 18 grams of drugs was found in a letter addressed to the 24-year-old sailor's off-base apartment, and a later search found more drugs in his residence.

The sailor was among a group of 12 U.S. sailors suspected for conducting an illegal drug trade since February, the news outlet said on its website.

Despite the allegations against the sailor, who serves on the aircraft carrier USS Ronald Reagan, the Japanese have not taken him into custody, believing the suspect would not flee or destroy related evidence after the U.S. Navy's involvement.

The sailor, who is unnamed, currently remains on duty.

The U.S. 7th Fleet, which includes U.S. naval forces stationed in Japan, saw a series of scandals since last year, when corruption and mismanagement has led to a slew of senior brass to face disciplinary action and multiple ship collisions that have killed dozens of sailors.