As Understanding of Russian Hacking Grows, So Does Alarm

Those behind the widespread intrusion into government and corporate networks exploited seams in U.S. defenses and gave away nothing to American monitoring of their systems

Legal prohibitions on the National Security Agency bar it from surveilling networks inside the United States. Photo: T.J. Kirkpatrick for The New York Times

By David E. Sanger, Nicole Perlroth and Julian E. Barnes