The laws regarding the president require that he have attorneys and advisors who have no Russian contact. That's to prevent conflict of interest. And it's also violation of USA laws again. Technically Sessions should not be advising Trump as he has Russian contacts who paid him very well. Laws were written that way so the president would not be influenced by Foreign governments. Rosenstein also has major Russian clients such as Putin, the first Russian Bank, and Kisylac.  Technically he should not be advising Trump too. I'm waiting for somebody to file charges in a court of law. I'm not holding my breath.