Russia Is Suspected to Be Behind Breach of Federal Court Filing System

Investigators have uncovered evidence that Russia is at least partly responsible for a recent hack of the computer system that manages federal court documents, including highly sensitive records with information that could reveal sources and people charged with national security crimes, according to several people briefed on the breach.

It is not clear what entity is responsible, whether an arm of Russian intelligence might be behind the intrusion or if other countries were also involved, which some of the people familiar with the matter described as a yearslong effort to infiltrate the system. Some of the searches included midlevel criminal cases in the New York City area and several other jurisdictions, with some cases involving people with Russian and Eastern European surnames.

The disclosure comes as President Trump is expected to meet with his Russian counterpart, Vladimir V. Putin, in Alaska on Friday, where Mr. Trump is planning to discuss his push to end the war in Ukraine.