The craft beer industry only accounts for about 5 percent of the $80 billion U.S. beer market -- peanuts compared to AB InBev, the maker of Budweiser and other beers, which commands a 39 percent share of that market.

But Goliath is very, very scared of David. The number of U.S. craft brewers jumped from 537 in 1994 to more than 2,000 as of July 2012, according to The Brewers Association, a national trade group. Meanwhile, Budweiser shipments in the U.S. declined 13 percent from 2009 to 2011, according to Beer Marketer’s Insights, a trade publication, and sales of Budweiser to U.S. retailers in the first nine months of 2012 fell by 6 percent in volume, Bloomberg reported.

The increasing popularity of craft beer was a major factor in AB InBev's decision to buy rival Grupo Modelo, Corona's parent company, according to internal documents from AB InBev released Thursday by the Justice Department, which sued to block the $21 billion purchase.

“We must slow the volume trend of High End Segment and cannot let the industry transform,” AB InBev said in internal strategy documents obtained by the Justice Department, referring to the threat posed by imports and craft beers.

In opposing the Modelo deal, the Justice Department argued that AB InBev's acquisition would serve to stifle competition in the U.S. beer market and lead to price increases. As a combined company, AB InBev and Modelo would command 46 percent of U.S. beer sales, the lawsuit said.

AB InBev said in a statement that it would “vigorously contest” the lawsuit. “The U.S. Department of Justice’s action seeking to block the proposed combination between AB InBev and Grupo Modelo is inconsistent with the law, the facts and the reality of the marketplace,” the statement said.

But the suit came as welcome news to some independent craft brewers, who feared the Modelo deal would enhance AB InBev's ability to pressure independent beer distributors to stop selling rival brands and craft beers.

Post-Prohibition era rules ban brewers in 38 states from distributing their own beers to retailers. As a result, a middle tier of roughly 3,000 independent distributors nationwide has emerged. Distributors provide transportation and storage for beer from the time it leaves a brewer until it arrives at a retailer such as a bar, restaurant or convenience store.

Steve Beauchesne, the owner of Ontario-based Beau’s All Natural Brewing Company, a 65-employee outfit that makes Bog Water Gruit Ale and Doc's Feet Dubbel, told HuffPost that his brewery only has access to one nearby wholesaler, and he fears that giants like AB InBev and MillerCoors will work to keep his product off delivery trucks.

“The size of the global beer companies right now is so ridiculous that it’s already gone beyond the point of making a difference whether one gets absorbed by another,” said Beauchesne. "They outspend us, they block entire markets, they do everything to keep us off tap."

Other craft brewers told HuffPost that while distribution was a cause for concern, they're not really worried about AB InBev encroaching on their turf.

"They don’t understand craft beer," said Fal Allen, the brewmaster at Anderson Valley Brewing Company in Boonville, Calif., who pointed to AB InBev's purchase of the craft brewery Goose Island in 2011 for $39 million. "They don't know how to market it," he added, "so instead of making craft beer, they’re now buying up companies who do."

Also on HuffPost:

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  • #20 - Great Lakes Brewing Company

    <strong>Location:</strong> Cleveland, Ohio <strong>Barrels Sold in 2011:</strong> 120,000 -- 31.9 percent increase since 2010 <strong>Popular Brands:</strong> Dortmunder Gold

  • #19 - Long Trail Brewing Company

    <strong>Location:</strong> Bridgewater Corners, Vt. <strong>Barrels Sold in 2011:</strong> 120,000 -- 10.1 percent increase since 2010 <strong>Popular Brands:</strong> Double Bag Ale

  • #18 - Abita Brewing Company

    <strong>Location:</strong> Abita Springs, La. <strong>Barrels Sold in 2011:</strong> 125,000 -- 14.7 percent increase since 2010 <strong>Popular Brands:</strong> Abita Jockamo IPA

  • #17 - Shipyard Brewing Company

    <strong>Location:</strong> Portland, Maine <strong>Barrels Sold in 2011:</strong> 129,000 -- 31.6 percent increase since 2010 <strong>Popular Brands:</strong> Shipyard Export Ale

  • #16 - Alaskan Brewing Company

    <strong>Location:</strong> Juneau, Alaska <strong>Barrels Sold in 2011:</strong> 130,000 -- 11.1 percent increase since 2010 <strong>Popular Brands:</strong> Alaskan Amber

  • #15 - Brooklyn Brewery

    <strong>Location:</strong> Brooklyn, N.Y. <strong>Barrels Sold in 2011:</strong> 140,000 -- 29.6 percent increase since 2010 <strong>Popular Brands:</strong> Brooklyn Lager

  • #14 - Dogfish Head Craft Brewery

    <strong>Location:</strong> Milton, Del. <strong>Barrels Sold in 2011:</strong> 144,000 -- 19 percent increase since 2010 <strong>Popular Brands:</strong> 60 Minute IPA

  • #13 - Stone Brewing Company

    <strong>Location:</strong> Escondido, Calif. <strong>Barrels Sold in 2011:</strong> 149,000 -- 29.6 percent increase since 2010 <strong>Popular Brands:</strong> Stone IPA, Arrogant Bastard Ale

  • #12 - Boulevard Brewing Company

    <strong>Location:</strong> Kansas City, Mo. <strong>Barrels Sold in 2011:</strong> 157,000 -- 5.4 percent increase since 2010 <strong>Popular Brands:</strong> Single-Wide IPA, Chocolate Ale

  • #11 - Lagunitas Brewing Company

    <strong>Location:</strong> Petaluma, Calif. <strong>Barrels Sold in 2011:</strong> 165,000 -- 55.7 percent increase since 2010 <strong>Popular Brands:</strong> Lagunitas IPA

  • #10 - Harpoon Brewery

    <strong>Location:</strong> Boston, Mass. <strong>Barrels Sold in 2011:</strong> 173,000 -- 15.3 percent increase since 2010 <strong>Popular Brands:</strong> Harpoon IPA, UFO Hefeweizen

  • #9 - Bell's Brewery

    <strong>Location:</strong> Galesburg, Mich. <strong>Barrels Sold in 2011:</strong> 180,000 -- 16.9 percent increase since 2010 <strong>Popular Brands:</strong> Bell's Lager, Java Stout

  • #8 - Matt Brewing Company

    <strong>Location:</strong> Utica, N.Y. <strong>Barrels Sold in 2011:</strong> 196,000 -- 7.7 percent increase since 2010 <strong>Popular Brands:</strong> Saranac

  • #7 - Deschutes Brewery

    <strong>Location:</strong> Bend, Ore. <strong>Barrels Sold in 2011:</strong> 223,000 -- 9.9 percent increase since 2010 <strong>Popular Brands:</strong> Red Chair NWPA, Mirror Pond Pale Ale

  • #6 - Magic Hat Brewing Company

    <strong>Location:</strong> South Burlington, Vt. <strong>Barrels Sold in 2011:</strong> 336,000 -- 4.3 percent increase since 2010 <strong>Popular Brands:</strong> #9, Single Chair

  • #5 - Spoetzl Brewery

    <strong>Location:</strong> Shiner, Texas <strong>Barrels Sold in 2011:</strong> 487,000 -- 13 percent increase since 2010 <strong>Popular Brands:</strong> Shiner Bock

  • #4 - Craft Brew Alliance

    <strong>Location:</strong> Portland, Ore. <strong>Barrels Sold in 2011:</strong> 635,000 -- 8.5 percent increase since 2010 <strong>Popular Brands:</strong> Widmer Brothers, Red Hook, Kona

  • #3 - New Belgium Brewing

    <strong>Location:</strong> Fort Collins, Colo. <strong>Barrels Sold in 2011:</strong> 713,000 -- 7.9 percent increase since 2010 <strong>Popular Brands: </strong> Fat Tire, Lips of Faith

  • #2 - Sierra Nevada Brewing Co.

    <strong>Location:</strong> Chico, Calif. <strong>Barrels Sold in 2011:</strong> 858,000 -- 9.2 percent increase since 2010 <strong>Popular Brands:</strong> Sierra Nevada Pale Ale, Ovila Abbey Ales

  • #1 - The Boston Beer Company

    Location: Jamaica Plain, Mass. Barrels Sold in 2011: 2,440,000 -- 8 percent increase since 2010 Popular brands: Samuel Adams, Twisted Tea