An Irish UFO expert believes that the unexplained phenomena are part of a global defense network that intercepts space-based threats. 

Speaking after NASA held its first-ever public meeting on UFOs on Wednesday, Patrick Jackson, who has been studying UFOs for more than 20 years, said he believed unexplained metallic orbs were part of a system that has defended Earth from external threats for possibly thousands of years. 

The NASA hearing heard that the space agency receives up to 100 UFO reports every month. However, only a tiny fraction - between 2 and 5% - are truly anomalous, said Sean Kirkpatrick, director of the All-domain Anomaly Resolution Office in the US Defense Department. 

However, Kirkpatrick also told the hearing that metallic orbs had been seen making "very interesting maneuvers". 

Jackson told the press that he has made the "overwhelming" discovery that the orbs are part of a global defensive system. 

"The spheres are a global defense network that intercepts space-based threats ranging from meteors to other space-based threats," he told the Sunday World.

Jackson added that he made the discovery while trying to understand poltergeist activity in the UK, stating that he once observed silver spheres flying around an allegedly haunted house.

He said the spheres were roughly the size of a tennis ball and "intelligently controlled". 

"I saw these orbs everywhere - the flight behavior was unusual, they would repeat the same patterns and processes," he told the Sunday World.  

Jackson added that the spheres operate like a scarecrow, scaring people away from areas of dangerous emissions on the pretense that the area is haunted by poltergeists. 

"You may hear a door banging in another part of the house. This action is designed to move people away, the further away a person is, the safer it is." 

He said the spheres send signals to larger spheres floating about 300 feet off the ground, which have baffled the US Navy

A third type of sphere operates higher in the sky and protects the planet from incoming threats, Jackson said. 

"They make a V formation and yes, they are protecting humans and I suspect, have been doing so for thousands of years.

"The orbs surround other UFOs and disable them. That’s what US Navy are seeing. They operate as triangles and re-configure. They look like stars in the sky, reported for centuries." 

Jackson said the orbs are visible through infrared, adding that they often appear during military air shows, with loud noises triggering their appearance. 

Wednesday's hearing heard that NASA and the Pentagon have obtained no evidence to link unidentified objects with extra-terrestrial life. 

"I want to emphasize this loud and proud: There is absolutely no convincing evidence for extra-terrestrial life associated with unidentified objects," said Dr. Daniel Evans, assistant deputy associate administrator for research at NASA.