Secretary of State Mike Pompeo fired back at ex-CIA Director John Brennan Sunday for saying North Korean leader Kim Jong Un has been "masterful" in "duping" President Trump, dismissing the comments as "silly."

"I think former Director Brennan's remarks are silly on their face," Pompeo said during an interview on "Fox News Sunday."

Pompeo shrugged off Brennan's concern that Trump was unrealistically raising expectations ahead of his historic summit with Kim on June 12 in Singapore.

"We're going to enter into a set of discussions with two nations doing their best to achieve outcomes for their own people that are consistent with their objectives and goals," Pompeo said.

"I think we now understand that there is the potential that there are shared objectives and our mission is to prepare the groundwork. We're pretty far along the way in doing so, and we'll continue to work in the days ahead," he added.

Brennan told MSNBC on Thursday he believed Kim has been strategically playing Trump.

"Kim Jong Un, who I despise because of the brutality that he has put upon the North Korean people, but unfortunately I think he has been masterful in how he has manipulated perceptions and how he has manipulated and quite frankly duped Mr. Trump," Brennan said.

"He escalated [tensions] in order to de-escalate and then to reach a plateau that allows him to retain that nuclear and ballistic missile capability, draw out negotiations over time, and in the meantime be able to get the economic benefits he has been looking for," he continued.

Brennan served as CIA director under former President Barack Obama from March 2013 to January 2017.

Pompeo, a Trump appointee, replaced Brennan as head of the spy agency before moving to his latest role leading the State Department on April 26, 2018.