“Nobody is listening to your telephone calls. That’s not what this program is about.”

Later, The Guardian and The Washington Post reported that the government is also gathering a huge amount of online information. The newspapers said the government can examine Internet users’ private emails, photographs and computer files. Reporters say at least nine major companies are taking part in the government program. They include Facebook, Google, Skype, YouTube, Hotmail, and Apple.

The program is called Prism. President Obama says Prism is directed mainly at people living outside the United States. If the government wants information about an American citizen or someone in the United States, officials must have permission from a special national security court.

But even foreign Internet date flows through the United States because its computer servers can carry information quickly and at low cost. Intelligence officers watch this communication to look for connections to known or suspected terrorists. They also look for data patterns that might show something about planned attacks.

President Obama says the intelligence-gathering programs have helped prevent terrorism. And, both programs are legal. They are protected under a measure Congress passed after the attacks on the United States on September 11, 2001. The law is called the Patriotic Act. It was designed to discover threats and prevent terrorist attacks.