WASHINGTON — The Pentagon has taken steps to prevent more disclosures but there is no guarantee against more damaging leaks after WikiLeaks published a huge trove of classified diplomatic cables, a spokesman said Monday.

Colonel Dave Lapan told reporters that the Defense Department had tightened procedures for handling sensitive information but he did not expect changes to rules on who is permitted access to secret documents.

The WikiLeaks website, which posted more than 250,000 classified documents on Sunday full of embarrassing details of diplomatic exchanges, has never revealed its source in a series of document dumps but suspicion has focused on a US Army private working in military intelligence, Bradley Manning, who is now under detention.

Given Manning's low rank, the Pentagon has faced questions over how it handles security clearances and secret information. But Lapan said the military was trying to achieve a "balance between security and information-sharing."

"Remember in the aftermath of 9/11, one of the major criticisms was that we had stovepipes and information wasn't being shared," he said.

"Only so many procedures can be put into place. Ultimately it's the responsibility of individuals to follow those."

The Defense Department on Sunday announced a series of measures to crack down on potential leaks, which included disabling all write capability for removable media on classified computers, restricting transfers of information from classified to unclassified systems and better monitoring of suspicious computer activity using similar tactics employed by credit card companies.

"It is impossible to know under what circumstances someone might be able to defeat the systems that are in place," Lapan said.

"So I couldn't guarantee that it (another leak) wouldn't happen, but the safeguards and procedures being put into place certainly lessen that chance."

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