A few months after 9/11, President Bush authorized the National Security Agency (NSA) to eavesdrop on Americans and others in the US without having to obtain the court warrants normally required in these situations, according to government officials. The New York Times reports that as a result, the NSA has monitored the international phone calls and e-mails of "hundreds, perhaps thousands" of people living in the United States.

Before Sept. 11, 2001, the NSA limited its spying in the US to foreign embassies and missions and obtained court orders for such investigations. Officials say the government still seeks warrants for entirely domestic surveillance.

The previously undisclosed decision to permit some eavesdropping inside the country without court approval was a major shift in American intelligence-gathering practices, particularly for the National Security Agency, whose mission is to spy on communications abroad. As a result, some officials familiar with the continuing operation have questioned whether the surveillance has stretched, if not crossed, constitutional limits on legal searches.

"This is really a sea change," said a former senior official who specializes in national security law. "It's almost a mainstay of this country that the NSA only does foreign searches."

The Times also reported the White House asked it not to publish the article, "arguing that it could jeopardize continuing investigations and alert would-be terrorists that they might be under scrutiny." As a result, the paper delayed publishing the article for a year, and omitted some information that the administration said would be useful for terrorists.