WASHINGTON -- Though President Barack Obama dramatically disclosed the existence of a covert Iranian nuclear enrichment site in front of world leaders Friday, U.S. and some foreign spy services have been watching the site for years.

The underground site near the holy city of Qom is one that the U.S., Britain and France "have followed for a few years," said a senior administration official. U.S. officials also regularly discuss Iran's nuclear program with Israeli officials.

A...