U.S. Secretary of State Hillary Clinton said her government "deeply regrets" the disclosure of information intended to be confidential in hundreds of thousands of secret U.S. State Department documents released by website WikiLeaks.
"I want to make clear that our official foreign policy is not set through these messages but here in Washington," she said. "Our policy is a matter of public record as reflected in our statements and our actions around the world."
Clinton also slammed the disclosure as "not just an attack on America’s foreign policy interests, it is an attack on the international community."
White House press secretary Robert Gibbs said U.S. President Barack Obama was briefed on the issue last week, after it become clear of the size and scope of the information that was about to become public.
What's a cable?
U.S. diplomatic cables - like the ones made available by WikiLeaks - are encrypted reports that are sent daily from the more than 270 American diplomatic outposts around the world to senior policy-makers in Washington, D.C.
In the 19th century, a country's overseas diplomatic staff would send sensitive messages home by telegraph, through cables buried under the sea. These types of messages were known as cablegrams, or cables. During times of conflict, countries would try to sabotage each other's underwater cables to prevent the flow of messages. The first commercial underwater cable was laid across the English Channel in August 1850.
Canadian diplomatic officials have also used the word "telex" to refer to these documents, according to an embassy source.
Today, undersea cables are far more sophisticated: while they can easily handle the few telegrams that are still sent out, the fibre-optic technology also transmits telephone traffic, the internet and private data traffic.
"I think that it’s safe to say that the president was, as an understatement, not pleased with this information becoming public," Gibb told reporters.
He said Obama would not comment Monday on the information leak.
Cannon speaks with Clinton on leaks
Earlier, Canadian Foreign Affairs Minister Lawrence Cannon said the revelations will not affect the country's "very strong" relations with the United States.
Speaking Monday in Gatineau, Que., Cannon told reporters he spoke "very briefly" with U.S. Secretary of State Hillary Clinton on Saturday about the documents, but was quick to downplay the significance of their content.
"I do find it deplorable that documents like this are leaked in this fashion, but I want to reassure everybody that I don't think this is going to change the strong relationship that we have with the United States," Cannon said.
Cannon's comment came as U.S. Attorney General Eric Holder said his department is conducting a criminal investigation into the leak of the diplomatic cables to WikiLeaks.
"This is not sabre-rattling," Holder said Monday morning, adding those found responsible will be held "fully accountable."
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News surfaced earlier on Monday that the Obama administration had ordered government agencies to review procedures immediately for safeguarding classified information in the wake of the WikiLeaks disclosure.
According to a memo obtained by The Associated Press, the Office of Management and Budget (OMB) has told agencies to establish security assessment teams to ensure that employees do not have broader access to classified information than is required for their jobs.
OMB director Jacob Lew said the failure of agencies to safeguard classified information is unacceptable and will not be tolerated.
The State Department said the leak has resulted in "significant damage" to national security, he said.
Details of the latest WikiLeaks release were first published Sunday in five international publications: the weekly German magazine Der Spiegel, the New York Times, England's Guardian newspaper, France's Le Monde newspaper and the Spanish newspaper El Pais.
WikiLeaks earlier gave them access to a cache of 250,000 documents, cables exchanged via the Secret Internet Protocol Router Network (SIPRNet).
WikiLeaks published 220 cables on its own website on Sunday. More cables were expected to be released throughout the week.
Condemnation 'in the strongest terms'
The United States says the release puts people's lives at risk.
"We condemn in the strongest terms the unauthorized disclosure of classified documents and sensitive national security information," Gibbs said in a statement Sunday.
He said the cables "could compromise private discussions with foreign governments and opposition leaders."
"When the substance of private conversations is printed on the front pages of newspapers across the world, it can deeply impact not only U.S. foreign policy interests, but those of our allies and friends around the world," Gibbs said in a statement.
"To be clear, such disclosures put at risk our diplomats, intelligence professionals and people around the world who come to the United States for assistance in promoting democracy and open government."
Republican Senator Lindsey Graham also condemned the disclosure, accusing WikiLeaks of having "blood on its hands."
"We're at war … [and] the world is getting more dangerous by the day," Graham said. "People who do this are low on the food chain, as far as I'm concerned.
"If you can prosecute them, let's try."
No danger in release: WikiLeaks
But WikiLeaks legal spokesman Mark Stevens said WikiLeaks founder Julian Assange made sure the release would not put anyone in danger.
"I think you'll find, if you look at it, there is no threat to either the security of individuals or ongoing operations," Stevens said.
The decision to publish the classified material was "not taken lightly," said New York Times reporter Andrew Lehren, who worked on the WikiLeaks story.
"Clearly the significance of this material is grave, and so a great deal of care was taken to go through and to determine what … could put lives at risk and deal with that material appropriately," Lehren said.
He said others at the Times met with White House representatives to review the documents and determine which among them were sensitive.
The Times described the cables as "a huge sampling of the daily traffic between the [U.S.] State Department and some 270 embassies and consulates."
The files cover three years of communications between U.S. diplomats and Washington, and some are dated as recently as late February.
SIPRNet has been described as a worldwide U.S. military internet system, kept separate from the ordinary civilian internet and run by the U.S. Defence Department in Washington.[GALLERY id=4177 cat=news]