Sony's PlayStation Network service for video games is back online after being disrupted Sunday by an online attack.

Separately, an American Airlines flight carrying Sony Online Entertainment President John Smedley was diverted to Phoenix while the online attack was happening, Sony Computer Entertainment spokesman Satoshi Nakajima said.

An individual or group called Lizard Squad claimed through a Twitter account there might be explosives on the plane, which was en route from Dallas to San Diego. The account also claimed responsibility for the attack on PlayStation Network.

It was still unclear if the account's claims were true, Nakajima said.

Sony confirmed via its PlayStation Twitter account shortly after 1 p.m. ET Sunday that its engineers were "aware of the issues and are working to resolve them."

Sony's network was compromised for about a month in 2011, including the personal data of 77 million user accounts. The network's security was upgraded to protect against such attacks.

Sony says there was no breach of personal information in the latest incident, which was resolved between Sunday night and Monday morning.

Smedley said on Twitter: "Yes, my plane was diverted. Not going to discuss more than that. Justice will find these guys."

American Airlines officials in Tokyo were not immediately available for comment.