Seven former U.S. Air Force personnel gathered in Washington Monday to recount UFO sightings over nuclear weapons facilities in decades past - accounts that a UFO researcher says show extraterrestrial beings are interested in the world's nuclear arms race and may be sending humans a message.

At a news conference at the National Press Club, the six former officers and one ex-enlisted man recalled either personal sightings or reports from subordinates and others of UFOs hovering over nuclear missile silos or nuclear weapons storage areas in the 1960s, '70s and '80s.

Three of the former Air Force officers - though they hadn't seen the UFOs themselves - told reporters that UFOs hovering over silos around Montana's Malmstrom Air Force Base in 1967 appeared to have temporarily deactivated some of the nuclear missiles.

Much of the testimony already has appeared in books, websites and elsewhere. But UFO researcher and author Robert Hastings, who organized the news conference, said the time has come for the U.S. government to acknowledge the UFO visits.

"I believe - these gentlemen believe - that this planet is being visited by beings from another world, who for whatever reason have taken an interest in the nuclear arms race which began at the end of World War II," said Hastings, who added that more than 120 former military personnel have told him about UFOs visiting nuclear sites.

"Regarding the missile shutdown incidents, my opinion ... is that whoever are aboard these craft are sending a signal to both Washington and Moscow, among others, that we are playing with fire - that the possession and threatened use of nuclear weapons potentially threatens the human race and the integrity of the planetary environment," he said.

Former Air Force Capt. Robert Salas - who has written a book about the Montana incidents - said he was underground when a UFO hovered over his missile silo in March 1967, and therefore couldn't see it. He said one of his guards above ground told him a red, glowing object about 30 feet in diameter was hovering just above the front gate of the facility, in an isolated area far from Malmstrom.

"And just as I [called my commander], our missiles began going into what's called a no-go condition, or unlaunchable. Essentially, they were disabled while this object was still hovering over out site," Salas said.

Salas and others said the military urged them at the time not to talk about the incidents.

Retired Col. Charles Halt recalled seeing UFOs over the woods near Royal Air Force Stations Bentwaters and Woodbridge in eastern England in December 1980. He and security personnel were investigating reports of strange lights just outside one of the bases.

"All through the forest was a bright glowing object," he said Monday. "The best way I can describe it, it looked like an eye - with bright red, with a dark center. It appeared to be winking. It was shedding something like molten metal, was dripping off it.

"It silently moved through the trees, avoiding any contact, it bobbed up and down, and at one point it actually approached us. We tried to get closer. It receded out into the field, beyond the forest, and silently exploded into five white objects - gone. So we went out into the field looking for any evidence, because something had been apparently falling off it - and we find nothing," he said.

He recalled subsequently seeing other objects in the sky, including one that stopped about 3,000 feet overhead and "sent down a concentrated beam at our feet." No one was harmed.

"The best way I can equate it is sort of a laser beam. We stood there in awe. Was this a warning? Was this an attempt to communicate? Was this a weapon? Or just a probe?" he said.

At about the same time, he was hearing radio reports from base personnel that beams from some of the objects were "falling into or near the weapons storage area."

In a staff meeting later, a general decided "it happened off base, so it's a British affair," Halt recalled. "In other words, they were loathe to get involved."

The Air Force investigated UFOs from 1948 to 1969 under a program eventually called Project Blue Book. The service, on its website, says the project concluded that "no UFO reported, investigated, and evaluated by the Air Force has ever given any indication of threat to our national security." It also says there has been "no evidence that sightings categorized as 'unidentified' are extraterrestrial vehicles."

Salas said the UFO phenomenon "is real, not imaginary."

"There is current excessive secrecy in our government surrounding this phenomenon," he said.

A reporter asked how many of the former military personnel subscribed to Hastings' theory that the message of extraterrestrials is that humans should get rid of nuclear weapons, and how many of them believed that we should get rid of nukes. Of the seven, it appeared that only Salas raised his hand.