Monaco, in her speech, said that the administration’s current tools for responding to cyber attacks include sanctions, indictments, diplomacy, and intelligence operations.
The OPM breach was first discovered in April and then determined to have begun around December.
Obama said after the G-7 summit in Germany that he would not identify the source of the OPM attack and instead said the vulnerability of federal computer networks is increasing.
The OPM revealed Friday that its investigation into the initial loss of personal data on 4 million federal employees had expanded and revealed that additional data was compromised, including sensitive information on some of the 700,000 government officials who hold security clearances and are involved in secret activities.
Monaco declined to comment when asked whether China was behind the cyber attack, as officials have said privately. However, she identified China and Russia as the main state-sponsored cyber threats, with Iran and North Korea as two others.