US Secretary of Defense Ashton Carter speaks about Russian airstrikes in Syria during a press briefing at the Pentagon in Washington, DC, September 30, 2015. (AFP/Getty/Saul Loeb)

Defense Secretary Ashton B. Carter used his personal email account to conduct some official government business early in his tenure at the Pentagon, he acknowledged Thursday, as the chairman of the Senate Armed Services Committee called for a review of his actions.

Carter’s practices violated Pentagon rules for the handling of email. Carter said he has changed his email practices, and that it was “entirely my mistake, entirely on me,” speaking to reporters while traveling in Iraq.

The secretary said that he doesn’t generally use email much, but that he did some “administrative work” using personal email installed on his iPhone, rather than a secure professional account. He did so even after a controversy erupted in which is was disclosed that Democratic presidential candidate Hillary Clinton used a personal email server for government business while serving as secretary of state, prompting an investigation.

“That I shouldn’t have been doing,” Carter said Thursday of his use of personal email. “Particularly someone in my position, and with the sensitivities about this issue, should have known better.”

“It’s not like I didn’t have the opportunity to understand what the right thing to do is,” he added. “I didn’t do the right thing. This is entirely on me.”

The news was first reported late Wednesday by The New York Times, which obtained copies of his emails through the Freedom of Information Act. According to the report, Carter continued the practice for at least two months. The emails showed him exchanging messages with several staff members, including Eric Fanning, who was then his chief of staff and has since been selected to be the new secretary of the Army.

When asked about Carter’s email practices Thursday afternoon, White House Press Secretary Josh Earnest said that Carter had moved to correct his mistake.

“He indicated that he didn’t frequently use personal email for government work,” said Earnest. “He says that those emails did not jeopardize the proper protection of classified information. It clearly is a mistake because it runs counter to our policy.”

Sen. John McCain (R-Ariz.), chairman of the Senate Armed Services Committee, said in statement Thursday that his committee will be looking into the matter.

“With all the public attention surrounding the improper use of personal email by other Administration officials, it is hard to believe that Secretary Carter would exercise the same error in judgment,” McCain said. “The Senate Armed Services Committee has requested copies of the emails and will be conducting a review to ensure that sensitive information was not compromised.”

The chief of staff for Rep. Duncan Hunter (R.-Calif.), a member of the House Armed Services Committee, downplayed the situation, saying Carter’s actions “wouldn’t be of much interest” had it not been for Clinton’s.

“Carter is the type of guy who can be taken at his word when he says it was a mistake, and no classified information passed through,” said Hunter’s chief of staff, Joe Kasper. “Though why create the exposure, and open yourself to the criticism, after all the controversy about personal emails? He has to know better, but if he didn’t, he most certainly does now.”

The Times received copies of 72 work-related emails with the request, according to their report. The emails were sent from Carter’s iPhone and iPad and discussed things such as television appearances, hotels bills and legislation.

In response to the report, Carter’s spokesman Peter Cook released a statement saying that Carter “rarely uses email for official government business.” However, Cook did say that Carter changed his email practices earlier this year.

“The Secretary believes that his previous, occasional use of personal email for work-related business, even for routine administrative issues and backed up to his official account, was a mistake,” Cook said. “As a result, he stopped such use of his personal email and further limited his use of email altogether. He is confident that his work-related email has been and will continue to be preserved within the federal records system.” 

A senior defense official said that Carter at that time was using his personal email in a way he believed complied with government rules. Carter himself appeared to contradict that Thursday, saying that a person in his position would have been briefed on how to handle email appropriately.

Greg Jaffe in Washington and Missy Ryan in Iraq to this story.