The US Air Force is investigating illegal drug use among troops protecting a nuclear missile base, officials said on Friday in the latest scandal to rock the country's nuclear force.

The probe is focusing on 14 enlisted airmen guarding the F.E. Warren Air Force Base near Cheyenne, Wyoming.

The troops, assigned to the 90th Missile Wing, are under investigation for "illegal drug activity while off duty," General Robin Rand, commander of Air Force Global Strike Command, told reporters during a telephone briefing.

The troops have been removed from duty pending the investigation's outcome, he said, declining to name the types of drugs involved.

The incident is the latest in a series of recent scandals involving missile launch personnel.

In 2013, General Michael Carey was relieved of his position as head of the 20th Air Force -- responsible for three nuclear wings -- after he was reported binge drinking and fraternizing with "two foreign national women" during a trip to Russia.

Soon after, dozens of officers from the 341st Missile Wing at Malmstrom Air Force Base in Montana were suspended after they were found cheating on a routine test of their knowledge about how to operate missiles. Two were also implicated in a drug case.

The Air Force uncovered the cheating when it was looking into illegal drug use on several bases.

Investigations by the Pentagon later revealed that missile corps members suffered from "burnout" from what they saw as unrewarding and stressful work in a force seen as a decaying backwater.

The Pentagon announced a major overhaul in November 2014, saying it would boost morale by spending billions of dollars upgrading ageing equipment, improving training and oversight and addressing security lapses.

Commenting on the nuclear force's latest black eye, Rand said "illegal drug use is incompatible with military service."

The F.E. Warren base is one of three installations hosting the country's 450 intercontinental nuclear missiles.

Global Strike Command oversees two of the US nuclear arsenal's three components, which includes Air Force bombers and intercontinental ballistic missiles and Navy submarines able to launch missiles at sea.

Of the 31,000 airmen assigned to Global Strike Command, Rand said, "the vast majority not only meets but exceeds the standards of the US Air Force."