"I inadvertently briefed the Vice President-elect and others with incomplete information regarding my phone calls with the Russian ambassador. I have sincerely apologized to the president and the vice president, and they have accepted my apology", Flynn wrote in his resignation letter, obtained by CNN. In fact, the White House confirmed media reports that Flynn spoke with the Russian ambassador about USA sanctions, precipitating his resignation, so the media reports were accurate.
Pence, relying on information from Flynn, publicly vouched that the retired Army lieutenant general did not discuss us sanctions against Russian Federation in calls late previous year.
Flynn's resignation came after details of the telephone calls were made public - increasing pressure on Trump to take action.
Gen Flynn resigned on Monday - less than a month into the job - after he allegedly discussed United States sanctions against Moscow with Russian ambassador Sergey Kislyak in a phone call late past year.
The calls for inquiries in Congress came as US media reported that Trump associates and staff had numerous contacts with senior Russian intelligence officials in the year before the November 8 presidential election, though no evidence of collusion was reported. Did the president know and when did he know it?
Napolitano said that Flynn, former director of the Defense Intelligence Agency, would have known that his conversations with Russian Amb.
"I think we should find out what's in them and then make the decision there", said Arizona senator John McCain, a leading critic of the Trump administration's relations with the Kremlin.
"The FBI must accelerate its investigation of the Russian connection with the Trump administration, and Congress must call for a bipartisan, independent, outside commission to fully investigate Russia's influence on the administration and the election", House Minority Leader Nancy Pelosi, D-Calif., said. But Flynn's denial that he had discussed sanctions with the ambassador, a claim that the vice president repeated in television interviews as recently as this month, was his ultimate downfall, administration officials say.
Kremlin spokesman Dmitry Peskov said Russian Federation would not be commenting on the resignation.
A second official said the justice department was concerned Mr Flynn could be in a compromised position as a result.
Several agencies are conducting the inquiries into Russia's efforts to meddle in the USA election and coordinating as needed, said the officials, who requested anonymity to speak about sensitive matters.
Flynn can resign. At minimum Flynn has become a distraction for the Administration.
We'll also check in on the planned meetings between President Trump and Canadian Prime Minister Justin Trudeau today and Israel's Benjamin Netanyahu on Wednesday, plus check in on California governor's race.
Former acting attorney general Sally Yates advised the White House in late January that Flynn may have broken the law by negotiating with a country in a diplomatic dispute with the US.