So far, these basic details are not in dispute. We know there was a meeting; we know who attended; and we know what they discussed.
Understanding what happened next is more complicated.
According to the New York Times, after the meeting, Cohen took a sealed envelope with the outline of the plan to the White House and delivered it to National Security Advisor Michael Flynn's office before Flynn's resignation. The Times' reporting, according to the paper, was based on Cohen's own assessment of what transpired.
Soon after, however, Cohen talked to the Washington Post and gave a very different version of events, saying he attended the meeting and took a written copy of the plan, but never delivered it to Flynn or anyone else at the White House.
Soon after, it was time for Version #3.
Cohen shifted his story again on Monday, telling Business Insider in a series of text messages that he denies "even knowing what the plan is." But he said in a later message that he met with Artemenko in New York for "under 10 minutes" to discuss a proposal that Artemenko said "was acknowledged by Russian authorities that would create world peace."
"My response was, 'Who doesn't want world peace?'" Cohen said.
Cohen added that even if he had taken an envelope with a Ukrainian peace plan to the White House, "So what? What's wrong with that?"
The answer is rooted in context. As Cohen probably knows, Donald Trump and his team are in the middle of a pretty significant scandal involving Russia and Putin's government illegally intervening in the American election in order to put Trump in power -- a series of claims the president and his team have made about the controversy that have since fallen apart under scrutiny.
With this in mind, when Trump's lawyer, Trump's business associate, and a pro-Putin politician -- who happens to have ties to Trump's former campaign chairman -- get together for a private chat, discussing a plan to reward Putin, it's hard to dismiss the meeting as trivial.
Meanwhile, Walter Pincus had a related report yesterday about the Russian scandal, and White House Chief of Staff Reince Priebus' recent comments to NBC News' Chuck Todd about White House officials talking to the FBI about the investigation.
That raises the question: What are the conflicts of interest involved with the White House talking with "FBI leadership" about whether a senior White House official "misled" or "lied" to agents? If Flynn lied to FBI agents, that could be a felony. Who from the White House, talked to whom at the FBI, about what?
Priebus went on to say, "We have talked about this. I think we've laid it out very clearly and now it's up to the DOJ [Department of Justice] and the FBI to take it any further, if that's what they do."
What did the White House lay out "very clearly?"