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(CNN) —  

Former Homeland Security Secretary Kirstjen Nielsen on Tuesday said she left office because “saying no” and refusing to do things that others in the administration wanted was “not going to be enough.”

“There were a lot of things that, there were those in the administration who thought that we should do, and just as I spoke truth to power from the very beginning, it became clear that saying no, and refusing to do it myself was not going to be enough, so it was time for me to offer my resignation,” she said at FORTUNE Most Powerful Women Summit.

Her comments came towards the end of an intense and brief interview with Amna Nawaz, national correspondent for “PBS NewsHour,” which focused primarily on Nielsen’s controversial role in the separation of families at the border.

Nielsen, who resigned in April, was pressed multiple times on whether she regretted signing a memo that enforced separating families.

“I don’t regret enforcing the law, because I took an oath to do that,” Nielsen said, adding that her decision was to “enforce the law, not to separate families.”

However, she said she wished the coordination and information flow had “worked a lot better.”

“What I regret is that we haven’t solved it and what I regret that that information flow and coordination to quickly reunite the families was clearly not in place and that’s why the practice was stopped through an executive order,” she said.

“It clearly wasn’t working, so we stopped it during an executive order,” she added.

When asked if anyone raised concerns that children would be traumatized as a result of the policy, Nielsen said, “not from staff, no.”

Earlier this month, President Donald Trump announced that he was going to nominate Nielsen to the National Infrastructure Advisory Council. Nielsen told the audience Tuesday that the position is unpaid and she would be advising the government on cyber and critical infrastructure needs.

Nawaz pressed her on why she was currently advising the White House, prompting a retort from Nielsen.

“Are you telling every CEO in here that they should never advise the government,” she said to applause.

This was Nielsen’s first public interview since her forced resignation in April. She had been scheduled to appear at the Atlantic Festival last month, but later dropped out amid backlash. She canceled due to a family situation, not the criticism over her attendance, according to a source familiar with the situation.

Singer-songwriter Brandi Carlile dropped out of the Fortune event earlier this week, citing the “atrocity of family separation.”

“Respectfully, I absolutely cannot support Kirstjen Nielsen having a voice among the most powerful and inspiring women in America,” she tweeted.

Nielsen became the face of the Trump administration zero-tolerance policy that led to the separation of thousands of families who were apprehended crossing the southern border.

At the end of the contentious interview, Nielsen said, ” I wish we had gotten to cyber, because that’s why I was originally here.”

“Cyber is the biggest threat that we face in the homeland today,” she said.