Reuters reports that unidentified hackers are claiming to have accessed and leaked the personal details of 40,000 U.S. troops, including members of the 25th Infantry Division and the 3rd Marine Division, along with those of more than 2 million South Korean ruling party workers (h/t SC Magazine).

"We have seen the sites where the details were posted and clips that supposedly capture the process of hacking into Web sites," an official the South Korean cyber security firm NSHC told Reuters -- though the official said it wasn't possible to verify the legitimacy of the data.

The attacks, which were launched on the anniversary of the start of the Korean War, also took down the Web site for South Korea's presidential office (Cheong Wa Dae) and several other sites.

"It is verified that not only Cheong Wa Dae and the Prime Minister's office but also some media outlets were hacked," a National Police Agency representative told Yonhap News. "It seems that a massive cyber attack has started."