Eshed said cooperation agreements had been signed between species, including an "underground base in the depths of Mars" where there are American astronauts and alien representatives.

"There is an agreement between the U.S. government and the aliens. They signed a contract with us to do experiments here," he said.

Eshed added that President Donald Trump was aware of the extraterrestrials' existence and had been "on the verge of revealing" information but was asked not to in order to prevent "mass hysteria."

"They have been waiting until today for humanity to develop and reach a stage where we will understand, in general, what space and spaceships are," Eshed said, referring to the galactic federation.

The White House and Israeli officials did not immediately respond to NBC News’ request for comment. Sue Gough, a spokesperson for the Pentagon, declined to comment.

A spokesperson for NASA said one of the agency's key goals was the search for life in the universe but that it had yet to find signs of extraterrestrial life.

"Although we have yet to find signs of extraterrestrial life, NASA is exploring the solar system and beyond to help us answer fundamental questions, including whether we are alone in the universe," the spokesperson said in a statement.

Eshed's ideas are spelled out in more detail in "The Universe Beyond the Horizon — conversations with Professor Haim Eshed" by Hagar Yanai published in November.

Eshed, who oversaw the launch of numerous Israeli satellites into space, said he was only speaking out now because attitudes were changing and people seemed more receptive.

"If I had come up with what I'm saying today five years ago, I would have been hospitalized," he told Yediot. "Today, they're already talking differently. I have nothing to lose. I've received my degrees and awards, I am respected in universities abroad."

In May, Trump said, "Space is going to be the future, both in terms of defense and offense ... we're now the leader on space," as he was presented with the official flag of a newly created military branch, Space Force.

Its focus, along with a Space Command, is on space as a military domain for the U.S., preserving satellites and communications and a focus on geo-politics in new terrain.

Eshed's comments immediately spawned jokes and theories online. At least half-a-dozen accounts have been created on Twitter claiming to be representatives to earth from the "Galactic Federation." Other users have asked for preferential treatment and meetings with the other-worldly group.

Nick Pope, who used to investigate UFOs for the British Ministry of Defense, described Eshed’s remarks as “extraordinary.”

“Either this is some sort of practical joke or publicity stunt to help sell his book, perhaps with something having been lost in translation, or someone in the know is breaking ranks,” he said.

Pope said the UFO and conspiracy theory community was excited but that questions remained including whether or not Eshed was speaking from direct personal knowledge and experience or whether he is repeating something he has been told.

“There are still some missing pieces of the puzzle here,” he said.

https://www.nbcnews.com/news/weird-news/former-israeli-space-security-chief-says-extraterrestrials-exist-trump-knows-n1250333