U.S. intelligence agencies warned the White House last year that President Trump’s personal lawyer Rudolph W. Giuliani was the target of an influence operation by Russian intelligence, according to four former officials familiar with the matter.

The warnings were based on multiple sources, including intercepted communications, that showed Giuliani was interacting with people tied to Russian intelligence during a December 2019 trip to Ukraine, where he was gathering information that he thought would expose corrupt acts by former vice president Joe Biden and his son Hunter…

The warnings to the White House, which have not been previously reported, led national security adviser Robert O’Brien to caution Trump in a private conversation that any information Giuliani brought back from Ukraine should be considered contaminated by Russia, one of the former officials said.

The message was, “Do what you want to do, but your friend Rudy has been worked by Russian assets in Ukraine,” this person said. Officials wanted “to protect the president from coming out and saying something stupid,” particularly since he was facing impeachment over his own efforts to strong-arm Ukraine’s president into investigating the Bidens.