President Trump’s transition team warned former national security adviser Mike Flynn that U.S. intelligence agencies were monitoring anyone who contacted Russian Ambassador Sergey Kislyak, according to a report published Friday evening.

Senior officials on Trump’s team alerted Flynn during a late November meeting that Kislyak’s communications were likely being monitored.

One month later, Flynn and Kislyak were recorded talking about rescinding U.S. sanctions against Russia, a conversation that later cost Flynn his position in the White House.

The transition team was worried that Flynn did not realize the gravity of the situation and asked the Obama administration to provide them classified information on Kislyak, though it’s not known if Flynn ever read the document, according to the Washington Post.

Democrats have warned of possible collusion between the Russian government and the Trump campaign, after Democratic Party entities were hacked during the presidential election. The emails were leaked publicly to damage Democratic presidential nominee Hillary Clinton.

While those claims remain unsubstantiated, the new report indicates even some members of Trump’s top advisers were worried about the image being cast regarding Flynn’s secret talks with Kislyak.