This just in: Michael Flynn has quit as national security adviser for Donald J. Trump.

Flynn resigned over questions relating to alleged conversations he had with Russian government officials prior to Trump becoming president of the United States. Reports have swirled that Flynn had talked about possible loosening of sanctions that the Obama administration had imposed to punish the Russians for their alleged role in interfering with the U.S. presidential election.

The Logan Act, anyone? It bars unauthorized personnel from negotiating with a foreign government. Flynn well might have broken federal law.

Now comes the question, to borrow an inquiry made famous in another serious matter: What did the president know and when did he know it?

Did the president know about Flynn’s conversations as they were occurring? Did he sanction them? Did the president hush it up?

The former acting U.S. attorney general, Sally Yates, wrote a report that suggested Flynn might have been “compromised” by his meetings with Russian officials. Yates then was fired over her refusal to enforce Trump’s ban on refugees from certain countries. Did the president know about these meetings in real time?

Trump now must find a new national security adviser. He has a long list of qualified, competent, knowledgeable individuals who can give him proper counsel regarding national security concerns.

Flynn, a retired Army lieutenant general, is known to be a brilliant military tactician and strategist. He also possesses intense feelings about Islam and has called that great religion a “cancer” on the world. I’ve heard two previous presidents — Barack Obama and George W. Bush — say we aren’t “at war with Islam.”

Gen. Flynn, though, got into trouble because of his relationships with Russian government higher-ups. There’s likely to be more to come in this regard.

I’m among those who want to know about what the big man in the Oval Office knew about these discussions — and when he knew it.