In an interview on Tuesday, former U.S. Ambassador to the United Nations Samantha Power sharply criticized President Donald Trump’s ouster of National Security Advisor John Bolton, saying the dismissal indicates an unsteady administration and the dispute over the termination’s details exemplifies a “deeper problem” of public trust.

“Instability in the world is never aided by instability at the center of the government that is the most powerful in the world,” says Power, who served for over three years as the U.S. Ambassador to the United Nations under President Barack Obama.

Trump announced the firing of Bolton on Twitter on Tuesday afternoon; soon after, Bolton tweeted a rebuke, saying that he had offered to resign on Monday night.

“We even see in the form in which this firing slash resignation occurred a deeper problem, which is nobody knows what’s true anymore,” Power says. “Trump said ‘I fired him,’ John Bolton said, ‘No actually I resigned or tried to resign.’ When America’s word is contested, when it’s questioned, that’s not good for our national security.”

Named as National Security Advisor last March, Bolton is widely known as a foreign policy hawk, reportedly clashing with Trump over the administration’s pursuit of a peace deal with the Taliban and its unwillingness to carry out a military strike in Iran in response to the downing of a U.S. surveillance drone, among other issues.

Power made the comments during a conversation that will air on Thursday in an episode of Yahoo Finance’s “Influencers with Andy Serwer,” a weekly interview series with leaders in business, politics, and entertainment.

The National Security Advisor is “the individual who talks to the president in principal when he wakes up in the morning and before he goes to sleep at night,” Power says. “It is meant to be an incredibly calming presence and it hasn’t been that in the case of Bolton’s tenure.”

“With John Bolton’s exit, Trump will be looking for his fourth national security advisor in under three years,” she adds. “That job is so important.”

Before she entered government, Power worked as a journalist and human rights advocate. In 2003, she won the Pulitzer Prize for “A Problem from Hell: America and the Age of Genocide,” an account of America’s role in protecting vulnerable people around the world.

On Tuesday, Power released a memoir entitled “The Education of an Idealist,” which chronicles her upbringing in Ireland and the United States, as well as formative moments throughout her career.

During the Obama administration’s first term, she served as a member of the National Security Council as Special Assistant to the President for Multilateral Affairs and Human Rights. In 2013, she became U.S Ambassador to the United Nations — a position Bolton held under Obama’s predecessor, President George W. Bush.

Andy Serwer is editor-in-chief of Yahoo Finance. Follow him on Twitter: @serwer.

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