The pages had been released in 2000 by the National Guard Bureau in response to requests made under the Freedom of Information Act.
"We mistakenly believed that these documents had been re-released earlier this year in response to earlier FOIA
requests," said a Department of Defense spokesman in an e-mail.
The documents, relating to the president's service in the Guard, include a few redacted lines.
"Because we do not have original copies of the documents that contain redactions, we are unable to determine exactly what has been redacted," said the DoD statement.
"We assume that the information redacted may include the social security number of President Bush and home address. If this assumption is correct, the only information this Office would redact would be the social security number which would be exempt pursuant to 5 USC § 552(b)(6) because its release would constitute a clearly unwarranted invasion of personal privacy," said the statement.