Michael Flynn resignation: He had to go, says White House

National security adviser Michael Flynn knew he had to resign after he misled the vice-president, a White House official has said.

"He knew he had become a lightning rod and he made that decision," Kellyanne Conway said of Mr Flynn on NBC's Today programme.

Mr Flynn resigned over allegations he discussed US sanctions with a Russian envoy before Donald Trump took office.

It is illegal for private citizens to conduct US diplomacy.

Mr Flynn, a retired army lieutenant-general, initially denied having discussed sanctions with Ambassador Sergei Kislyak, and Vice-President Mike Pence publicly denied the allegations on his behalf.He later said he could not recall whether he discussed the sanctions.

"In the end, it was misleading the vice-president that made the situation unsustainable," Ms Conway said on Tuesday.

Senior Republican and House Speaker Paul Ryan also weighed in on Tuesday, noting Mr Trump had "made the right decision" in asking for Mr Flynn's resignation
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"You cannot have a national security adviser misleading the vice president and others," Mr Ryan said at a news conference.His comments contrast the account offered by White House aides, who have insisted Mr Flynn resigned voluntarily.