The day Russian ambassador Sergey Kislyak mingled with Trump campaign advisers—including then-Sen. Jeff Sessions—at a conference near the Republican National Convention, the Department of Homeland Security began preparing a nationwide warning about foreign intelligence officials attempting to elicit information from U.S. government personnel at conferences, events, and other functions.

The document, eventually released on July 27, 2016, and reviewed by The Daily Beast, doesn’t specifically mention which foreign intelligence service might be making such contacts. But a senior administration official says that growing concern within U.S. government circles about Russian interference in the election generally—and Kislyak’s presence at the RNC in particular—was “not unrelated” to the production of the DHS intelligence bulletin.

Another source confirms the connection, pointing to a section of the bulletin warning of attempts by foreign intelligence officials “to gather intelligence through what appears to be normal, even mundane, social or professional contact” at events including conferences.

This article is based on DHS and other counterintelligence documents and interviews with five current or former law enforcement, intelligence, and government officials with deep knowledge of aspects of the overarching investigation into Russian influence of American politics. Not all of the sources agreed about the importance of the bulletin. Some viewed it as routine and somewhat obvious given its timing just months before an election; others believed it to be a serious indication of the FBI’s long-running investigatory interest in Moscow’s attempts to sway the American political process.