So Trump’s National Security Adviser Robert O'Brian warned him that his lawyer
Rudy Giuliani has been worked by Russian assets in Ukraine, and that any information Giuliani brought back from Ukraine should be considered contaminated by Russia.
And Trump shrugged it off and dismissed concern about his lawyer’s activities by saying, “That’s Rudy.”
At this point, one might be able to say that Rudy in an unwitting Russian asset.
But since Trump was warned and is still perfectly willing to use information that he was warned should be considered contaminated by Russia, that would probably make him a witting Russian asset.