The U.S. Department of Homeland Security (DHS) is reportedly assisting in the investigation into the intrusion that may have exposed millions of PSN users' personal data to unauthorized intruders.

"The Department of Homeland Security is aware of the recent cyber intrusion to Sony's PlayStation Network and Qriocity music service," DHS spokesman Chris Ortman told government technology site NextGov. "DHS' U.S. Computer Emergency Readiness Team [CERT] is working with law enforcement, international partners and Sony to assess the situation."

Computer hacking has been an increasing focus for the anti-terrorism department in recent years, but the cabinet-level division is usually focused on foreign and domestic attacks on computer infrastructure critical to government functions or public services.

DHS occasionally assists in investigating hacks on important non-government entities, however, as it did in the case of a suspected 2010 attack on the NASDAQ stock exchange's systems.

CERT can help compromised companies restore service and implement new protocols to improve future security in these cases. The group also helps share knowledge of known vulnerabilities with other public and private sector organizations, to prevent similar attacks from happening in the future.

There is some concern among security experts that personal data gleaned from the PSN breach could help hackers with identity theft or cracking schemes focused on corporate or financial services.

Sony announced Tuesday that PSN user data may have been compromised after first shutting down the service last week. The company said Wednesday that encrypted credit card data was likely safe, though it could "not rule out the possibility" such data had been taken.

Australia's ABC News reports the country's Privacy Commissioner is investigating Sony's security protections in the attack's wake, following on a similar investigation by the UK's Information Commissioner.