Kelly: Barring 'change,' he's not quitting or being fired

President Donald Trump is expected to pick Kirstjen Nielsen above to lead the Department of Homeland Security. Alex Brandon  AP

White House chief of staff John Kelly told the White House press corps Thursday that one of President Donald Trump's frustrations "is you".

"A state that has developed a pretty good ICBM (missile) capability and is developing a pretty good nuclear re-entry vehicle, I would believe ... that that state simply can not have the ability to reach the homeland", Kelly said.

Reports on his imminent departure are greatly exaggerated, the retired general says. He said: "This is hard, hard work and my only frustration, with all due respect to everyone in the room, is when I come to work in the morning and read about things I allegedly said, or things Mr Trump allegedly said, or people who are going to be fired or whatever, and it's just not true".

Kelly took issue with the notion that he is a "failure" for not controlling Trump's frequent tweeting, which has not stopped during his tenure as chief of staff. 'I don't believe, and I just talked to the president, I don't think I'm being fired today'.

Kelly called the job the hardest and most important job he's ever had, but not the best job he's had, saying that that the best job he's ever had was when he was an enlisted Marine.

"I was not sent in or brought in to control him, and you should not measure my effectiveness as a chief of staff by what you think I should be doing, but simply the fact is I can guarantee to you that he is now presented with options, well thought out options", Kelly said. "I look forward to working closely with the Administration and Ranking Member McCaskill to expedite the consideration of Ms. Nielsen's nomination and help make America safer and more secure".

Prior to joining Kelly at Homeland Security, Nielsen was president of the firm Sunesis Consulting.

Although Trump recently declared that secretary of state Rex Tillerson was "wasting his time" trying to negotiate Pyongyang, Kelly added: "Let's hope diplomacy works".

Nielsen formerly served as John Kelly's deputy when he held the post of Trump's first DHS secretary.