NSA Flynn met with the Russian ambassador before taking office
Flynn, who was fired as head of the Defense Intelligence Agency by the Obama Administration for abuse of subordinates, inefficiency, a "loose relationship with facts," and insubordination, has denied the conversation, which may be in violation of the Logan Act forbidding negotiations between private American citizens and foreign governments.
Flynn, a strong Islamophobe who is also strongly pro-Russian, did not offer or receive any quid pro quo during the conversation, the official told NBC News. Flynn, Trump spokesman Sean Spicer, and Vice-President Mike Pence have all denied that the conversation took place.
The critical concern is that the president and members of his administration could stand to profit from the dropping of sanctions due to their investments in Russia.
ADDENDUM: Seems I jumped to a conclusion here. Gen. Flynn, who was fired Tuesday, discussed the sanctions imposed by President Obama after the revelations about the FSB's interference with the election, not the Ukraine sanctions. This came as reports surfaced that representatives of the Trump campaign had met with the Russians several times prior to the election.