Given the task definition and input, reply with output. Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.

Sentence: Under mounting pressure from new revelations that the United States collected the telephone data of tens of millions of Europeans , the Obama administration on Monday said that there is a need for new constraints on U . S . intelligence - gathering operations and a top senator announced that the spying on U . S . allies would stop .<sep>Span: U . S . intelligence - gathering operations
Which agency did this?