Mike Pompeo takes oath as Secretary of State

Former CIA director Mike Pompeo was today sworn-in as the US Secretary of State and immediately vowed to look into the "flawed" Iran nuclear deal criticised by President Donald Trump.

Pompeo , 54, was administered the oath of office by Vice President Mike Pence. He replaces Rex Tillerson, who was fired by President Trump in March.

He is the 70th Secretary of State.

Trump drove down to the State Department for the formal swearing in ceremony of Pompeo. This was his first trip to the State Department.

Ahead of the swearing in ceremony, President Trump praised Pompeo as "a true American patriot".

"He has devoted many years of his life to defending America beginning when he entered West Point, and as you all heard, he entered at 18 and ended up graduating first in his class," Trump said.

In remarks following his oath, Secretary of State Pompeo touted the work the Department has done under the Trump administration, including considering next steps for the "flawed" Iran nuclear deal, CNN reported.

"We are but 15 months into this administration and we've made an outstanding progress by speaking the truth about the challenges we face, by confronting them head on," Pompeo said.

"We're confronting all types of Iranian hostility and are deciding on the next steps for the flawed JCPOA."