Donald Trump's latest Russia expert has reportedly been escorted from the White House amid claims of a security-related investigation.
He is the third head of European and Russian affairs at the National Security Council to leave the post in the past year.
It was not immediately clear what the reported security investigation involved.
In a series of eccentric TV appearances he has claimed that the US state department asked him to get involved.
It is also believed that the investigation into the company, Burisma, had long been dormant.
It's another thing, I thought, to leverage security assistance -- security assistance to a country at war, dependent on both the security assistance and the demonstration of support." »