Two British members of the hacking group LulzSec admitted Monday carrying out cyber attacks against the CIA and Rupert Murdoch's British newspaper group News International.
Ryan Cleary, 20, and Jake Davis, 19, pleaded guilty at London's Southwark Crown Court to charges that they launched distributed denial of service (DDoS) attacks on the organisations' websites last year, a court official said.
The activity involves overwhelming websites with simultaneous requests, resulting in the sites shutting down.
The pair also targeted Britain's Serious Organised Crime Agency (SOCA) and the Arizona State Police as well as entertainment giants Nintendo, Sony and 20th Century Fox.
They denied charges however of "posting unlawfully obtained confidential computer data to public websites" such as the hacking group's own site, LulzSec.com.
Cleary, who comes from the Shetland Islands off Scotland and has been diagnosed with Asperger's syndrome, also admitted to four separate charges, including an attack on Pentagon computers.
The United States filed an indictment against Cleary earlier this month, naming him as "an associate of the hacking group LulzSec (Lulz Security), an offshoot of the larger group Anonymous", according to the US attorney's office and FBI officials in California.
"Cleary identified weaknesses in targeted computer networks for LulzSec colleagues, who were allowed to wage attacks using an army of virus-infected computers at his command," said US Attorney Andre Birott and Steven Martinez, assistant director-in-charge at the FBI field office in Los Angeles.
"Cleary assisted LulzSec in its hacking activities by identifying and exploiting security vulnerabilities on victim computers, conducting DDoS attacks, and providing access to servers and other computer resources for LulzSec members to use," Birott and Martinez said in a joint statement at the time.
US authorities will not seek to extradite Cleary, according to British reports.
Cleary will face trial in London in April 2013, while Davis, from Wickford in Essex, southeast England, will be tried in October this year.
Their alleged accomplices, Ryan Ackroyd, 25, from Mexborough, northern England, and a 17-year-old from south London, who cannot be named for legal reasons, deny carrying out the DDoS attacks and posting unlawfully obtained material online.
Explore further: Second apparent leak of hacked celebrity nude pictures: US media