Two “sophisticated adversaries” linked to Russian intelligence services broke into the Democratic National Committee’s computer networks and gained access to confidential emails, chats and opposition research on presumptive Republican nominee Donald Trump, the party and an outside analyst said Tuesday.

The firm CrowdStrike said it was approached by the DNC to investigate a potential breach of its systems, which began as early as last summer. Immediately, CrowdStrike found on the DNC’s computer some of the “best adversaries” in the hacking arena tied to the Russian government.

DNC chairwoman Debbie Wasserman Schultz called the incident “serious” and said the committee moved quickly to “kick out the intruders and secure our network.” The DNC said donor, financial and personal information didn’t appear to have been accessed by the hackers.

But an individual familiar with the breach said at least a year’s worth of detailed chats, emails and opposition research on Trump were stolen. That research, a staple of political campaigns, often contains detailed information about a candidate’s personal and professional history.

The individual, who spoke only on condition of anonymity because he was not authorized to discuss the breach, said DNC officials first learned about the hack in late April when its technology staff discovered malware on its computers.

CrowdStrike said one of the hacking groups identified, dubbed Cozy Bear, had previously infiltrated unclassified networks at the White House, the State Department and the Joint Chiefs of Staff.

Another group detected, called Fancy Bear, had targeted private and public sector networks around the world since the mid-2000s. The two groups involved in the hacking had penetrated the system separately, CrowdStrike said.

The incident was first reported Tuesday by The Washington Post.

(AP)