WASHINGTON (AFP) - The United States' spy chief lashed out on Saturday at what he called "reckless" press disclosures about US intelligence agencies' data mining programs, defending them as tools to fight terror.
Director of National Intelligence James Clapper intervened after newspapers revealed the National Security Agency has a system in place to access foreign citizens' email and other data through firms like Google and Microsoft.
In a second statement on the subject this week, Mr Clapper said the programme is "vital" in keeping the US and its allies safe and "continues to be one of our most important tools for the protection of the nation's security."
"Over the last week we have seen reckless disclosures of intelligence community measures used to keep Americans safe," he added. "In a rush to publish, media outlets have not given the full context - including the extent to which these programmes are overseen by all three branches of government - to these effective tools."
Mr Clapper stressed that the surveillance activities are lawful and that the US Congress had "fully debated" the programme, which was recently reauthorised under Section 702 of the Foreign Intelligence Surveillance Act.
The Foreign Intelligence Surveillance Court - a specially established federal court with 11 judges - the executive branch and Congress all have oversight over the surveillance programs.
According to leaked documents obtained by The Guardian and The Washington Post, a NSA program known as PRISM allows the NSA and FBI to track someone's Web presence via analysis of audio, video, photographs, emails and connection logs.
Mr Clapper dubbed PRISM "an internal government computer system used to facilitate the government's statutorily authorised collection of foreign intelligence information from electronic communication service providers under court supervision."
He said the program, authorised under FISA, "has been widely known and publicly discussed since its inception in 2008." The spy chief also stressed that "the US government does not unilaterally obtain information" from private US service providers' servers.
"Service providers supply information to the government when they are lawfully required to do so," he added.
Mr Clapper emphasised that the program cannot intentionally target US citizens or anyone known to be living in the United States.
And he said the government cannot target a foreign national outside the US "unless there is an appropriate, and documented, foreign intelligence purpose for the acquisition."