Angela Merkel with Edmund Stoiber in 2002, the year when American surveillance on her began, according to a database.
WASHINGTON — It was not obvious to the National Security Agency a dozen years ago that Angela Merkel, a rising star as the leader of the Christian Democratic Union, was a future chancellor of Germany.
But that did not matter.
The N.S.A., in a practice that dates back to the depths of the Cold War and that has never ended, was recording her conversations and those of a range of leaders in Germany and elsewhere, storing them in databases that could be searched later, if the need arose. It is unclear how often they searched the databases for her conversations, if at all.
But once she became the country’s leader, everything she talked about on her personal cellphone — like her support of the Afghan war, the efforts of European allies to halt Iran’s nuclear program, and Germany’s central role in quelling the European financial crisis — took on greater importance for the American eavesdroppers.
How the N.S.A. continued to track Ms. Merkel as she ascended to the top of Germany’s political apparatus illuminates previously undisclosed details about the way the secret spy agency casts a drift net to gather information from America’s closest allies. The phone monitoring is hardly limited to the leaders of countries like Germany, and also includes their top aides and the heads of opposing parties. It is all part of a comprehensive effort to gain an advantage over other nations, both friend and foe.
What the United States has learned from Ms. Merkel’s calls since 2002, the year when surveillance on her began, according to a database described last week in the German newsmagazine Der Spiegel, remains unknown. But no one has denied that she was being monitored.
In testimony to Congress on Tuesday, the director of national intelligence, James R. Clapper Jr., gave only the roughest sketch of the size of the N.S.A.’s surveillance program, but suggested that the leader of the United States’ most powerful European ally was a single fish in a very big sea.
“We’re talking about a huge enterprise here with thousands and thousands of individual requirements,” he said, using a phrase that appeared to mean individual surveillance targets. Mr. Clapper said that the United States spies on foreign leaders and other officials to see “if what they’re saying gels with what’s actually going on,” and how the policies of other countries “impact us across a whole range of issues.”
German political and intelligence officials went to the White House on Wednesday looking for answers to some of the questions the administration has been reluctant to discuss, and eager to use the incident to broker a far closer intelligence-sharing agreement with Washington that, among other things, would end the surveillance of its leaders.
If put into effect, such an arrangement could begin to dismantle a system that has grown ever larger, and more sophisticated, during a decade in which supercomputers and the algorithms used to search vast databases have put the N.S.A. far ahead of rival intelligence services. President Obama has asked whether the technology has outrun common sense, and the Merkel episode has raised in a very public way the question of whether the benefits of spying on friends outweigh the damage if such spying becomes known.
Even after the flood of information about surveillance operations made public by Edward J. Snowden, the former N.S.A. contractor, American officials are still loath to speak in detail about eavesdropping on friendly governments. But former officials with knowledge of the system described an intelligence apparatus with both a voracious appetite and a growing ability to warehouse huge amounts of data.
The N.S.A. tries to gather cellular and landline phone numbers — often obtained from American diplomats — for as many foreign officials as possible. The contents of the phone calls are stored in computer databases that can regularly be searched using keywords.
“They suck up every phone number they can in Germany,” said one former intelligence official.
The databases are different from those housing telephone “metadata” — information about phone numbers on each end of a call and the call’s length — to find links between terrorism suspects. “Metadata is only valuable if you are trying to track the activities of a terrorist or a spy,” said the former American intelligence official.
Alison Smale contributed reporting from Berlin, and Mark Landler from Washington.
