Adm. Mike Mullen, the top U.S. military officer, gestures during a news conference Tuesday in Baghdad. Mullen, the chairman of the Joint Chiefs of Staff, says the leak of U.S. military documents about Afghanistan could put American lives in danger. He told reporters that he was “appalled” by the leak, and said “there is a real potential threat there to put American lives at risk.”

Washington ? Dismayed by the massive war-documents leak, intelligence experts are raising alarms that post-Sept. 11 changes promoting information sharing have made it too easy to lose control of the nation’s secrets.

Some intelligence veterans say it’s time to rethink how widely classified material is shared at lower levels or, at the very least, to step up monitoring of the people who are given access.

“Frankly, we all knew this was going to happen,” says former CIA Director Michael Hayden. He predicts “a new emphasis on protecting.”

The intelligence failures that led to the attacks of 9/11 were blamed on government agencies hoarding information instead of sharing it, missing crucial clues that could have headed off al-Qaida’s strikes. The changes that reduced this kind of information “stovepiping” have produced the opposite problem — amassing so much data that officials complain it’s hard to make sense of it, and, as the WikiLeaks incident shows, keep it secret.

Both intelligence officials and outside experts suggested that agency chiefs may push to limit access to electronic “portals” that have provided growing data access to intelligence officers, diplomats and troops around the world. And others predicted tighter scrutiny by an administration that has already pushed aggressively to investigate and prosecute leakers.

On the other hand, some lawmakers on Capitol Hill worry that the leaking incident will give the nation’s 16 intelligence agencies an excuse to go back to old ways of holding back some information as “too sensitive” to be shared.

“The intelligence community has a long way to go in information sharing,” says Sen. Kit Bond of Missouri, top Republican on the Senate Intelligence Committee. “If these leaks lead to even more stovepipes,” as in limiting access to data to only certain analysts or agencies, “it would be yet another devastating result of this betrayal,” he said.

Rep. Anna Eshoo, D-Calif., a House Intelligence Committee member who shares those concerns, conducted a closed hearing Tuesday on information sharing.

Eshoo would not detail what went on at the hearing, but she said that “it’s the nature of the intelligence community to hoard information.” Despite the WikiLeaks episode, she said she would still push for “more information sharing in the intelligence community, not less.”

Suspicion for the WikiLeaks document dump centers on Spc. Bradley Manning, of Potomac, Md., a 22-year-old soldier who is being detained in Kuwait, charged with “mishandling and leaking classified data.”

Manning was blamed for leaking a classified helicopter cockpit video of a 2007 firefight in Baghdad. Detained after he bragged of providing classified material to WikiLeaks, Manning was later charged with accessing what were described as more than 150,000 classified State Department cables, which have yet to surface.

So far, no U.S. official has directly linked Manning to the WikiLeaks documents.

One U.S. official who has examined some of the WikiLeaks documents said everything he’d seen could have been obtained by Manning by surfing a Defense Department intranet system known as the “SIPRNet,” or Secret Internet Protocol Router Network. The official spoke on condition of anonymity to discuss matters of intelligence.

Intelligence analysts like Manning and even troops in the field can access military field reports from Iraq or Afghanistan, or State Department sites, or even some intelligence sites.

The SIPRNet is not new, but access to it has grown since Sept. 11, 2001, to make information available to those who need it as the nation engaged in two wars.

The government has also put more information on SIPRNet by adding more portals giving users access to non-Defense Department information systems such as Intelink, an inter-intelligence agency data-sharing system. Many of these portals require passwords to reach more “top-secret” information, as opposed to the less-restricted “secret” material made available by WikiLeaks.