WASHINGTON - US President Donald Trump's national security adviser, Michael Flynn, resigned on Monday night in the midst of a raging controversy about his contacts with Russian officials before Trump took office, a White House official said.
Retired General Keith Kellogg, who has been the chief of staff at the National Security Council, has been named acting national security adviser.
The Justice Department earlier warned the White House weeks ago that Flynn could be vulnerable to blackmail for contacts with Russian officials before President Donald Trump took power.
The U.S. official confirmed a Washington Post report that Sally Yates, the then-acting U.S. attorney general, told the White House late last month that she believed Flynn had misled them about the nature of his communications with the Russian ambassador to the United States.
She said Flynn might have put himself into a compromising position, possibly leaving himself vulnerable to blackmail, the official said. Yates was later fired for opposing Trump's temporary entry ban for people from seven mostly Muslim nations.
Flynn had told Pence he had not discussed U.S. sanctions against Russia with Russian officials in the weeks before Trump took office on Jan. 20, prompting Pence to defend him in subsequent television interviews.
In recent days, Flynn has acknowledged he might have discussed sanctions with the Russians but could not remember with 100 percent certainty, which officials said had upset Pence, who felt he had been misled.
Officials said Flynn apologized to Pence twice, including in person on Friday.
Flynn, a retired U.S. Army lieutenant general, was an early supporter of Trump and shares his interest in shaking up the establishment in Washington. He has frequently raised eyebrows among Washington's foreign policy establishment for trying to persuade Trump to warm up U.S. relations with Russia.
Top White House officials have been reviewing Flynn's contacts with the Russians and whether he discussed the possibility of lifting U.S. sanctions on Russia once Trump took office.
That would potentially be in violation of a law banning private citizens from engaging in foreign policy, known as the Logan Act.