Rep. John Tierney (D-MA), the ranking Democrat on the House Oversight and Government Reform Committee's National Security Subcommittee, slammed Republicans on Thursday for conducting a hearing that he said was driven by Internet conspiracy theories suggesting that the Department of Homeland Security (DHS) was buying a billion rounds of ammunition to use against the American people.

In his opening statement on Thursday, subcommittee Chairman Jason Chaffetz (R-UT) cited "recent news reports" about the "federal government's massive procurement of ammunition."

"The question is, what is an appropriate use of this ammunition, where is it stored, how much are they paying for it and what are they doing with it?" the Utah Republican asked.

Although Chaffetz mentioned media outlets like The Associated Press and USA Today, much of the hype about DHS ammunition purchases have been driven by conservative websites like Alex Jones' Infowars and Glenn Beck's The Blaze. And the theories have been kept alive by the Fox News Channel, the Fox Business Network and even televangelist Pat Robertson.

"To the extent that we're responding to conspiracy theories or whatever, I think we're really wasting everybody's time on that," Tierney said in his opening statement. "It might have been predictable that Sarah Palin would have taken opportunity to feed these conspiracy theories with statements that the government was preparing for civil unrest, but it was a little more disturbing that Sen. Chuck Grassley (R-IA) would seize the opportunity to accuse the government cornering the market on ammunition to drive up prices."

"Unsubstantiated false conspiracy theories have no place in this committee room -- hopefully," he continued. "Federal ammunition purchases are a fraction of the total ammunition market and they've been decreasing in recent years. Even the National Rifle Association distances itself from these conspiracy theories."

Watch this video from the House Oversight and Government Reform Committee's National Security Subcommittee, broadcast April 25, 2013.