The top executives of Google, Facebook and other Silicon Valley firms on Friday fiercely denied they gave intelligence officials broad access to data about their users.
The statements sharply contradict the language in a National Security Agency document that described the companies' participation in a secret surveillance program called PRISM. The National Security Agency document referred to "collection directly from the servers" of nine Internet companies.
The conflict between the PRISM document and the company statements could be the result of imprecision by the document's author.
Technology and security experts offered other explanations, with some arguing that the firms had carefully crafted their denials to leave open the possibility that they had participated in PRISM in some way. Nearly all of the companies cited in the NSA document said the government does not have "direct access" to their servers. But that leaves open the possibility that the government has indirect access to their technology.
Other experts said the government could be scooping up the data as it travels across Internet networks. The data is often encrypted, and a company could fulfill a government request by handing over the encryption keys.