The Defense Advanced Research Projects Agency, better known as DARPA, tweeted the appeal on Wednesday.
"Attention, city dwellers!" the tweet read. "We are interested in identifying underground tunnels and facilities owned or commercially managed by the University."
"It's short-term," they admitted. "We ask for an answer by 5:00 pm ET on August 30th."
It hung a row of photos – a dimly lit parking garage, an underground bunker with Polish signage and an empty subway station – and a link to the official proposal on a government website.
People were understandably suspicious.
After all, these are the people who brought us stealth weapons, the M1
The Department of Energy did not respond to a CNN request for comments.
However, DARPA told CNN that the tweet was not a cause for concern.
"DARPA received a request for university-owned or commercial information last week managed subterranean tunnels and facilities, and yesterday's posts in social media reminded of the upcoming deadline for response, "said Jared B. Adams, chief communications officer of DARPA, to CNN.
"Complex urban underground infrastructures can present significant challenges to situational awareness Time-critical scenarios such as active hostilities or disaster response," Adams explained.
So the next time you explore a deserted tunnel deep under a US city and rush by, do not worry, this is an autonomous killer Cave Robot.
Just keep going. Fast.