Trump was angry James Mattis was perceived as the 'only adult in the room': CNN
U.S. President Donald Trump at the Pentagon in Washington, U.S., January 27, 2017. REUTERS/Carlos Barria

In a rebuke of the president's decision to withdraw troops from Syria, Secretary of Defense James Mattis submitted his resignation on Thursday.

CNN reporter Kaitlan Collins revealed that the relationship between Trump and Mattis had deteriorated during an interview with CNN host Erin Burnett.

"Mattis tried to get Trump to change his decision on Syria, but he rebuffed him," Collins said. "Things have not been good between the president and Mattis for some time now, they have grown icy."

She then said that Trump was mad that he was not perceived as an adult.

"President Trump has grown irritated with the narrative that Mattis was the adult in the room," she said.

Watch below via CNN.