WASHINGTON — Weeks before the Democratic convention was upended by 20,000 leaked emails released through WikiLeaks, another little-known website began posting the secrets of a top NATO general, billionaire George Soros’ philanthropy and a Chicago-based Hillary Clinton campaign volunteer.

Security experts now say that site, DCLeaks.com, with its Capitol-dome logo, shows the marks of the same Russian intelligence outfit that targeted the Democratic organizations.

The emails and documents posted to the DCLeaks site in early June suggest that the hackers may have a broader agenda than influencing the U.S. presidential election, one that ranges from the Obama administration’s policy toward Russia to disclosures about the hidden levers of political power in Washington.

It also means the hackers may have much left in their grab bag to distribute at will.

The biggest revelation involves four-star U.S. Gen. Philip Breedlove, formerly the top military commander of NATO. Emails show him complaining that the White House wasn’t paying enough attention to European security. (“I do not see this WH really ‘engaged,’ ” he writes, wondering “how to work this personally with the POTUS.”) The Intercept subsequently wrote about the emails, inflaming tensions between the U.S. and its European allies.

Breedlove told CNN in July that the emails were stolen as part of a state-sponsored intelligence operation.

The leaks highlight the effectiveness of some of the hackers’ tricks, including the targeting of private email accounts to gather sensitive military and political intelligence. DCLeaks also offers some insight for investigators on what appears to be the hackers’ early missteps and ad hoc approach.

A cache of hacked Google emails from a Clinton volunteer, for example, doesn’t add up to much: They purport to be from the account of Sarah Hamilton, who works for a public relations firm in Chicago and volunteers for Hillary for America, and show little but the harried schedule of the campaign staff.

Similarly, a trove of “redacted” documents from the William J. Clinton Library have been publicly available on the library’s website for years, a spokeswoman for the library said.

Security experts see links to a larger Russian operation. That’s in part because the email addresses of Breedlove and Hamilton were among thousands targeted in a several-month campaign that began last fall by a Russian hacking group.