Deare reportedly criticized the Trump administration's handling of Latin American policies during a speech at The Wilson Center Thursday in Washington. He also criticized overall White House dysfunction a source said.
Fielding questions about Deare's reassignment, Sanders said that people who don't agree with President Donald Trump should not have a job in his White House.
Deare's reassignment returns him to the National Defense University, an appointed position he's held since January 2001.
This is not the first time a senior administration official has been removed from their post because of comments about Trump.
Republican consultant Shermichael Singleton, a political appointee at the Department of Housing and Urban Development, was fired last week for an op-ed he wrote before the election that criticized then-candidate Trump, a source with knowledge of the situation said.
"We allowed that hostile takeover to happen on our watch," he wrote. "This individual recognized a moment of great disparity in the Republican base and, like cancer, attacked and spread, consuming everything in his path."
However, some of Trump's closest aides have also criticized him in the past.