The Twitter and YouTube accounts belonging to U.S. Central Command were apparently taken over by hackers who said they are loyal to the Islamic State group.
The Twitter account on Monday posted threats to U.S. soldiers, warning "We are coming watch your back. ISIS."
Follow-up tweets included pictures of documents that appeared to contain the telephone numbers, email addresses and home addresses of dozens of U.S. military officials.
CENTCOM officials confirmed to VOA its Twitter and YouTube sites were attacked and said they are taking "appropriate measures to address the matter."
The account also leaked what appeared to be military maps of China and North Korea. The authenticity or significance of the documents could not be confirmed, but some of the leaked material had already been available on the Internet and did not appear to be sensitive.
Central Command, based at MacDill Air Force Base in Florida, handles American military operations covering the Middle East and Central Asia. It oversaw the wars in Iraq and Afghanistan and is managing the U.S. airstrikes against Islamic State positions in Iraq and Syria.
'We are in your PCs'
In some cases, the material posted on Twitter appeared juvenile or incoherent, including one picture of a goat in an office with the caption "we are in your PCs" and a profile photo that contained the message, "I Love You, ISIS."
At a regular press briefing, White House spokesman Josh Earnest said the incident is "something we are looking into and it is something we take seriously."
But Earnest downplayed the attack, saying there is a "difference between a large data breach and the hacking of a Twitter account."
Within 30 minutes, the CENTCOM Twitter and YouTube accounts were suspended. While still under control of the hackers, two crudely produced Islamist propaganda videos appeared on the Central Command YouTube page.
Hackers claiming allegiance to the Islamic State group had previously taken over the Twitter accounts of several news organizations in the states of Maryland and New Mexico.
Some of the threats and hashtags in those cases appeared similar to the Tweets that appeared on the CENTCOM Twitter on Monday.
Within 30 minutes, control of the CENTCOM Twitter account appeared to be taken back by U.S. officials, though the official CENTCOM YouTube page was still controlled by the hackers.
Obama on cyber security
The Monday attacks took place at the same time President Barack Obama was delivering a speech on expanding cyber security.
In a speech Monday, at the Federal Trade Commission in Washington, D.C., Obama said data hacking presents a direct threat to American consumers.
In outlining newly proposed legislation, Obama said companies will have to alert customers within 30 days if their personal data has been compromised. The move follows several major security hacks at some of the country's largest retailers, including Target and Home Depot.
Other proposals include providing adults with free access to their credit scores and preventing student data from being sold to a third party.
The proposals are expected to make up part of the president's State of the Union address on January 20. It is unclear whether the Republican-led Congress will take up either of the proposals.