WASHINGTON  The U.S. military says it has captured at least six al-Qaeda media centers in Iraq and arrested 20 suspected propaganda leaders since June.

The seizures of the centers underscore the importance al-Qaeda has placed on media, primarily the Internet, as a tool to communicate to its members and use against U.S. forces in Iraq. The group's media emphasis continues to increase, intelligence analysts say.

Al-Qaeda is keenly aware that the battle is ultimately for the "hearts and minds of the ummah," the community of Muslim believers, says Gordon Woo, catastrophe analyst for RMS, a London-based firm that consults private companies on terrorism risks. Woo notes that Ayman al-Zawahri, Osama bin Laden's deputy, said in 2005 that most "of this battle is taking place in the battlefield of the media."

The progress against al-Qaeda's media operations stems from new offensives aimed at al-Qaeda sanctuaries and an emphasis on blunting the terrorist group's extensive propaganda operations, U.S. officers say.

"One of our goals is to target these propaganda networks, and we've had more success over the past three months," says Air Force Col. Donald Bacon, a staff officer at Multi-National Force-Iraq.

Those seizures have sharply curtailed the amount of videos and other communications posted to the Internet from Iraq, Bacon says.

Recent U.S. efforts have made it difficult for al-Qaeda's Internet operations, but such successes are hard to define and may only be temporary, says Rita Katz of the SITE Institute, which monitors terrorist websites. The SITE Institute noted al-Qaeda in Iraq's recent distribution of a 20-minute video, called "The Astray Arrow," alleging the failure of the coalition's offensive in Diyala province, Operation Arrowhead Ripper.

Al-Qaeda's media output in Iraq dipped starting five or six weeks ago, Katz says, but it has since recovered.

The group often uses the Internet to raise money and attract recruits, the U.S. military says. Al-Qaeda's militants are ordered to film every attack they conduct on coalition or Iraqi forces, Bacon says. Music is often added to the edited package, for effect.

For some Arab viewers who don't regularly view Western media, the overwhelming impression from the videos could be that militants are winning. The benefit for militants is to turn a single attack into a larger strategic weapon.

Along with the raids in Iraq, the Pentagon also is developing plans to attack computer networks and websites used by terrorists, military records show.

Gen. David Petraeus, the top U.S. commander in Iraq, told Congress last month that the "war is not only being fought on the ground in Iraq but also in cyberspace."

Petraeus has "placed a greater command emphasis on the media war," says Maj. Winfield Danielson, a military spokesman in Iraq.

The terrorist group's media centers are nondescript from the outside but jammed with production equipment, Bacon says. One house raided recently in Samarra, north of Baghdad, included 12 computers, 65 hard drives and a filming studio.

The U.S. military says it has uncovered media operations in the past, but not as many as in recent months. It is not clear how many centers exist, Bacon says.

Contributing: Richard Willing