But drawing a line from Snowden to the Paris tragedy is problematic, according to some analysts, because even two years after the leaks it is difficult to isolate the extent to which they caused terrorist networks to change the way they communicate.

The revelations that were the source of greatest controversy involved programs that would likely have been of little value in disrupting the Paris plot, experts said. The National Security Agency’s collection of data about the times and durations of billions of domestic phones calls was not designed to pick up calls entirely outside the United States.

A second program that relied heavily on cooperation from companies including AOL, Microsoft and Google was aimed at intercepting e-mail and phone calls between foreign operatives and individuals in the United States. Nothing has changed since that revelation to restrict the NSA’s ability to sweep up communications exclusively among foreigners, as was apparently the case for the plot in France.