Obama: 'Top secret' beer operation under White House

"That's top-secret," said Obama on CBS's "Late Show With David Letterman" Tuesday. "No, we make a few bottles for events when people come over to the White House."

A much-speculated-about construction project at the White House was completed earlier this month, which was officially a utilities upgrade, but the underground changes continue to be a mystery, according to The Associated Press.

When pressed on whether the beer making was legal, Obama said, "I don't know."

"We started making it and then somebody said, 'Do we need a license for this?' " he said.

Obama told Letterman that the idea to brew beer was born from excess honey made by the bees in the White House garden.

An amateur brewer who works in the White House mess offered to experiment with a beer using the leftover honey, according to Obama.

"He made a few bottles and it was some tasty stuff, so we've got a little operation going there and if the presidency thing doesn't work out, we've got a little microbrewery thing going on," Obama said.

The beer gained attention after an online petition called for the release of the hoppy recipes. The White House posted the recipes on Sept. 1 for White House Honey Ale and White House Honey Porter on its official blog.

Watch the full episode with Obama on CBS, including the president's reaction to Romney's fundraiser video.

Read more on Obama's expectations for cooperation in the Middle East on The Hill's Blog Briefing Room.