The White House made the unusual declaration in response to a feature on its website that allows people to submit petitions that administration officials must respond to if enough people sign on.
In this case, more than 5,000 people signed a petition demanding that the White House disclose the government's knowledge of extraterrestrial beings, and more than 12,000 signed another petition seeking formal acknowledgement of an extraterrestrial presence engaging the human race.
In response, Phil Larson of the White House Office of Science and Technology Policy wrote that the U.S. government has no evidence that life exists outside Earth, or that an extraterrestrial presence has contacted any member of the human race.
"In addition, there is no credible information to suggest that any evidence is being hidden from the public's eye," Larson wrote.
But he didn't close the door entirely on a close encounter of an alien kind, noting that many scientists and mathematicians believe that, statistically speaking, odds are high that there is life somewhere among the "trillions and trillions of stars in the universe" - although odds of making contact with non-humans are remote.
It's not the first petition to force the White House to engage on a somewhat off-beat topic since the "We the People" webpage was unveiled in September. The White House also has been forced to explain why it can't comment in response to a petition demanding "Try Casey Anthony in Federal Court for Lying to the FBI Investigators" (because it's a law enforcement matter).
And various petitions demanding legalization of marijuana have gathered more than 100,000 names, to which the White House argues that marijuana is associated with addiction, respiratory disease and cognitive impairment, and legalizing it would not be the answer.
The White House also has addressed topics including gay marriage and student loan debt.
When the website debuted, the White House promised to respond to any petition that garnered 5,000 or more signatures within 30 days, but it's now raised that threshold to 25,000.
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Online: http://www.whitehouse.gov/wethepeople
