The Pentagon called the hacking of the Central Command’s (CENTCOM) YouTube and Twitter accounts Monday “cyber vandalism” in a letter to service members and their families to allay concerns about the incident. General Lloyd Austin said that the FBI is investigating the “alleged breach” of the two social media sites by hackers who claimed to be aligned with the Islamic State (ISIS). While Austin said that “CENTCOM network was not compromised and no classified information,” he acknowledged that the hackers posted “information obtained from the accounts,” he did not go into further detail.

Austin also referred to “the threat of ‘lone wolf’ attacks by individuals who align with or are sympathetic to radical Jihadist elements,” examples of which, according to Austin, are the “recent tragedies in Paris…New York City and Ottawa, Canada.” The general acknowledged that Monday’s hacking included threats, but said there were no “no credible threats made to U.S. military personnel or their families.”