The accounts – the CENTCOM Central Command Twitter and YoutTube accounts – appeared to have been taken over by sympathisers of the so-called Islamic State group.
A number of messages were then posted on the CENTCOM Twitter page, including some appearing to threaten American soldiers.
White House Press Secretary Josh Earnest said the accounts had since been suspended, adding the extent of the incident was being looked into.
“There’s a pretty significant difference between what is a large data breach and the hacking of a Twitter account. So we’re still examining and investigating the extent of this incident,” he told reporters.
Two pro-Daesh videos also appeared to have been added to the CENTCOM YouTube account.
US President Barack Obama is currently preparing new proposals to better protect the country from cyber security threats.
