The Democratic White House front-runner's campaign says she "pledged to cooperate with the government's security inquiry."
Hillary Clinton's campaign said Tuesday night that she will provide her private email server and a thumb drive containing her messages to the Justice Department, which is reviewing the security of the unusual email arrangement she used as secretary of State.
"She directed her team to give her email server that was used during her tenure as secretary to the Department of Justice, as well as a thumb drive containing copies of her emails already provided to the State Department," campaign spokesman Nick Merrill said.
"She pledged to cooperate with the government's security inquiry, and if there are more questions, we will continue to address them," he said.
The FBI is reviewing the security of the email system that Clinton used when she was secretary of State, as first reported last week by The Washington Post. The inquiry follows a "security referral" to the Justice Department by I. Charles McCullough III, the inspector general for federal intelligence agencies due to the IG's concerns about the presence of classified information in some of Clinton's messages.
The campaign's announcement comes just hours after the revelation that McCullough told lawmakers in a memo Tuesday that Clinton's emails stored on her private server included at least a small number of messages that contained "top secret" information.
On Tuesday evening, Senate Judiciary Committee Chairman Chuck Grassley released a memo from McCullough that adds new detail to the previous finding by the intelligence IG and the State Department IG that at least four of Clinton's emails contained classified information.
There are at least two emails that include information classified up to "top secret"—which is the highest classification category—while two others are under review at the State Department for a determination on their classification, the memo states.
The finding is certain to inflame GOP political attacks against Clinton at a time of already-intense scrutiny of the Democratic White House front-runner's unusual private email arrangement.
The memo to top lawmakers on several committees responds to inquiries about a July memo from McCullough about a limited review that turned up classified information in four emails, although they did not have classification markings or "dissemination controls" at the time.
The State Department is not currently endorsing McCullough's claim that two of Clinton's messages contained "top secret" information.
"The Intelligence Community has recommended that portions of two of the four emails identified by the Intelligence Community's Inspector General should be upgraded to the Top Secret level. Department employees circulated these emails on unclassified systems in 2009 and 2011 and ultimately some were forwarded to Secretary Clinton. They were not marked as classified," State Department spokesman John Kirby said Tuesday night.
Kirby said that State will ensure the information is protected while his agency works with the Director of National Intelligence to "resolve whether, in fact, this material is actually classified."
His comments underscore the ongoing lack of consensus among officials about classification.
A senior State Department official said it's common that in cases of "parallel" information gathering from sensitive and publicly available sources, "the source from which the information is derived is critical in determining classification."
"It is common for State Department employees to learn information from open sources, including press reports, that may also be independently learned through entirely separate means within the Intelligence Community," the State Department official said.
Clinton's campaign has said she did not send or receive emails that were marked classified at the time.
Grassley, in a statement, cheered the new details about classification provided by McCullough to lawmakers.
"I appreciate the intelligence community inspector general providing more information in response to the questions that many members of Congress and the public have regarding the classified emails that were on former Secretary of State Clinton's private server and on a thumb drive with her private attorney. This information revealed by the inspector general makes it even more important that the FBI and the State Department secure these documents," Grassley said in a statement made before the campaign's announcement.
Late last year, Clinton gave the State Department 55,000 pages of her work-related emails from her time as secretary of State. The department, acting under a court order, has been releasing them monthly in batches, with the next set due at the end of August.
"As she has said, it is her hope that State and the other agencies involved in the review process will sort out as quickly as possible which emails are appropriate to release to the public and that the release will be as timely and transparent as possible," Merrill, the campaign spokesman, said Tuesday night.
While disclosing that the server and thumb drive would be turned over to the Justice Department, he also sought to downplay concerns about the security of the devices, noting, "Her team has worked with the State Department to ensure her emails are stored in a safe and secure manner."
McCullough has previously informed lawmakers Clinton's work-related emails were copied to a thumb drive in the possession of Clinton attorney David Kendall.
Kendall told the House Select Committee on Benghazi in March that Clinton's emails from her tenure as secretary of State are no longer on the server itself.