“Utilizing what D.O.D. can provide — a large and trained cybersecurity work force to protect against and respond to cyberintrusions, and a strong focus on national security — is the right step to take,” Mr. Schumach said.

In the breach at the personnel agency, about 22 million records were stolen by the intruders — widely believed to be Chinese, though the administration has avoided publicly naming the Chinese government as the offender. The records include Social Security numbers; medical and financial histories; the names of friends, family members and people from past relationships; and, in more than six million files, complete fingerprints.

The attackers lurked undetected in the system for more than a year. Only when long-delayed system upgrades began did the scope of the theft become clear, or the stealth with which the data was shipped out of the databases, some of which were located in the Interior Department.

The overhaul was announced without fanfare on a quiet day in Washington, an hour before federal offices closed to prepare for a huge snowstorm. Mr. Obama had no public schedule on Friday, and the daily White House briefing was canceled because of the weather.

It was not clear how quickly the changes would take effect. White House officials said that they “will take time to fully implement,” and that a transition team would manage the formation of the new office. It will absorb the existing entity responsible for background checks, known as Federal Investigative Services.

The new office will have “a senior privacy official to advance privacy by design,” referring to the concept of building security measures into products from their inception, rather than after a devastating breach.

“We are committed to protecting the security of not only our systems and data, but also the personally identifiable information of the people we entrust with protecting our national security,” administration officials who conducted the review of the background check system wrote in a blog post announcing the overhaul. Among the officials who signed the post were James R. Clapper Jr., the director of national intelligence, and Beth Cobert, the personnel office’s acting director.

Since the revelations last year of the data theft, the personnel agency has rushed to bolster the security of its information. Mr. Schumach said it had moved to put in place “real-time monitoring” of its computer systems, installed controls to bar unknown devices from logging on to its network, and enforced “two-factor authentication” for gaining access to the network — a basic measure that had been lacking on many government systems.