Both the White House official and the former military official requested anonymity to discuss the matter. "There are no personnel announcements at this time".
The reports suggest possible candidates to replace McMaster.
Despite making the acknowledgment, Hicks said she had not lied about matters in connection with the investigation into alleged Russian meddling in the 2016 presidential election.
But efforts to move McMaster back to the Army have been stymied by two issues: Trump has had trouble finding a high-quality replacement who is willing and able to take over, and it is also not clear that McMaster, still an active-duty general officer, has any place to go in the Army. The economic advisor publicly criticized the administration and reportedly drafted a letter of resignation following the president's response to Charlottesville-where Trump blamed "both sides" for terrorist attacks executed by white supremacists-but stayed on to helm tax reform and infrastructure initiatives.
A national-security adviser's influence is often dependent on having a close relationship with the president.More news: IOC reinstates Russia's Olympic membership
At today's White House press briefing, White House Press Secretary Sarah Huckabee Sanders was grilled briefly on the recent controversies surrounding senior advisor (and President Donald Trump's son-in-law) Jared Kushner that have popped up in recent days.
"The United States will expose and act against those who use cyberspace, social media and other means to advance campaigns of disinformation, subversion and espionage", McMaster said.
Speaking to reporters, Sanders said Trump thinks McMaster is doing a "great job" and that the security adviser "isn't going anywhere".
An administration officials says McMaster will likely not return to the military and will instead retire as a three-star general.
McMaster joined the administration a year ago after Trump fired his predecessor, Michael Flynn, for lying to Vice President Mike Pence.