washington — embattled national security adviser michael flynn's fate as one of president donald trump's senior aides is uncertain following reports that he discussed u.s. sanctions with a russian envoy before trump's inauguration.

a top white house official sidestepped repeated chances sunday to publicly defend him. the president, who spent the weekend at his private club in florida, has yet to comment on flynn's status. nor has vice president mike pence, who previously denied that flynn had discussed sanctions with sergey kislyak, the russian ambassador to the u.s.

pence and flynn spoke twice on friday, according to an administration official.

trump has told associates he is troubled by the situation, but he has not said whether he plans to ask flynn to step down, according to a person who spoke with him recently. flynn was a loyal trump supporter during the campaign, but he is viewed skeptically by some in the administration's national security circles, in part because of his ties to russia.

the administration official and both people with ties to trump spoke on the condition of anonymity to discuss private conversations.

stephen miller, trump's top policy adviser, skirted the issue on several sunday news shows, saying it was not his place to weigh in on the "sensitive matter" or to say whether the president retains confidence in flynn.

several other white house officials did not respond sunday to questions about whether trump had confidence in his national security adviser. their silence appeared to reflect some uncertainty about the views of the president, who is known to quickly change his mind.

on friday, the washington post reported that flynn addressed sanctions against russia in a call with kislyak. the report contradicted repeated denials from trump officials, including pence, who vouched for flynn in a televised interview.

flynn has since told administration officials that sanctions may have come up in the calls, which coincided with the obama administration slapping penalties on russia for election-related hacking.

new jersey gov. chris christie, who led trump's transition planning before the election, said flynn would have to explain his conflicting statements about his conversations with kislyak to trump and pence.

"gen. flynn has said up to this point that he had not said anything like that to the russian ambassador. i think now he's saying that he doesn't remember whether he did or not," christie said on cnn. "so, that's a conversation he is going to need to have with the president and the vice president to clear that up, so that the white house can make sure that they are completely accurate about what went on."

the controversy surrounding flynn comes as the young administration grapples with a series of national security challenges, including north korea's reported ballistic missile launch. the president, who was joined at his mar-a-lago estate by japanese prime minister shinzo abe over the weekend, voiced solidarity with japan.

trump meets monday with canadian prime minister justin trudeau and later in the week with israeli prime minister benjamin netanyahu.

the white house is also dealing with fallout from the rocky rollout of trump's immigration executive order, which has been blocked by the courts. the order was intended to suspend the nation's refugee program and bar citizens of seven muslim-majority countries from entering the u.s.

advocacy groups contend the government has rounded up large numbers of people as part of stepped-up enforcement. the agency calls the effort no different from enforcement actions carried out in the past.