Trump’s White House staff 'love their country and love their president': Nikki Haley Haley said everyone who loves this country "should support this president."

 -- The Trump administration's ambassador to the United Nations, Nikki Haley, disputed allegations in an explosive new book, "Fire and Fury: Inside the Trump White House," that people around the president question his intelligence and fitness for office.

"I know those people in the White House," Haley told ABC News Chief Anchor George Stephanopoulos on "This Week" Sunday. "These people love their country and respect our president ... No one questions the [mental] stability of the president."

She added, "These people put everything they've got into their jobs and into respecting and trusting the president. If they didn't they wouldn't be there."

Haley herself testified to Trump's strengths and stability.

"I work with the president and speak with him multiple times a week," the U.N. ambassador said. "He didn't become the president by accident, and as much as everyone wants to talk about stability: Was he unstable when he passed the tax reform? Was he unstable when we finally hit back at Syria and said, 'no more chemical weapons'? Was he unstable when we finally put North Korea on notice?"

"We need to be realistic [about] the fact that every person regardless of race, religion or party who loves this country should support this president," Haley said. "It's that important."

Haley also addressed the question of U.S. policy on North Korea after the president on Saturday appeared to open the door to direct talks with the regime of Kim Jong Un.

Stephanopoulos noted that Trump previously said it would be a waste of time for Secretary of State Rex Tillerson to try to negotiate with North Korea.

"Why the turnaround?" Stephanopoulos asked.

"There is no turnaround," Haley responded. "What he has basically said is, 'Yes, there could be a time where we talk to North Korea but a lot of things have to happen before that actually takes place.' They have to stop testing. They have to be willing to talk about banning their nuclear weapons."

She added of the nuclear threat from North Korea, "The reality is this is a very dangerous situation."

Stephanopoulos also asked about Trump’s tweet last week saying that he has a “much bigger [and] more powerful” nuclear button than Kim Jong Un.

Haley defended the president's tweet, saying North Korea knows “we're not letting up on the pressure. We're not going to let them go and dramatize the fact that they have a button right on their desk and they can destroy America. We want to always remind them we can destroy you too, so be very cautious and careful with your words and what you do.”

The president "always has to keep Kim on his toes,” Haley said. “It's very important that we don't ever let him get so arrogant that he doesn't realize the reality of what would happen if he started a nuclear war."