Donald Trump has told the US intelligence service: "I am so behind you."
On his first full day in office, Mr Trump said the CIA has been "restrained" in the past and not "used the real abilities" available to them.
He added that the CIA are "really special amazing people", and that "very few people could do" their job.
Speaking to 400 employees at the CIA headquarters in Langley, Virginia, he reiterated a key campaign promise and said: "We have to get rid of Islamic State.
"Radical Islamic terrorism has to be eradicated - this is evil."
His speech follows repeated and sharp public criticism of the CIA before and after the election.
Trump challenged their conclusions that Russia attempted to influence the election to help him win.
All weekend it felt as though the new administration had a self-destruct button and was desperately searching for it.
White House press secretary Sean Spicer appears to be enraged that the press told the truth about the size of the Trump inauguration crowd.
White House press secretary Sean Spicer said the inauguration crowd had been 'the largest audience to ever witness an inauguration, period'.