Lonnie Bunch, the outgoing secretary of the Smithsonian Institution, has defended the organisation against political interference, insisting that telling the unvarnished and complex truths of history is an act of “great love” for the country.

Speaking on Friday at the National Museum of African American History and Culture in Washington, Bunch received a standing ovation from hundreds of audience members and rejected claims that the institution’s staff or exhibitions were unpatriotic.

“The notion that somehow this museum or any part of the Smithsonian is done by people who don’t love America, don’t care about America, is unbelievably wrong,” the secretary said. “And what you see in this building is great love. Great respect.”

Bunch, who earlier this month announced that he will step down at the end of the year, was speaking at an event celebrating the 10th anniversary of the African American museum, where he was founding director.

His remarks come amid escalating hostility from Donald Trump’s administration, which issued a report accusing Smithsonian leaders of being radical activists and ordered a wide-ranging review of museum content ahead of the US’s 250th anniversary.

Last year Trump wrote on his Truth Social platform: “The Smithsonian is OUT OF CONTROL, where everything discussed is how horrible our Country is, how bad Slavery was, and how unaccomplished the downtrodden have been – Nothing about Success, nothing about Brightness, nothing about the Future.”

But on Friday Bunch argued that slavery is “foundational” to understanding the US. “When people say you talk too much about slavery or that they’re embarrassed by slavery, I wish I was as strong as my enslaved ancestor. I wish I could believe in America that they believed. I wish that I could dream a world anew that they dreamed.

“So for me, it’s not saying, ‘Oh my god, I’m going to be embarrassed, I’m trying to hurt a country.’ I’m trying for people to understand, how did these people believe? How did they lay this foundation that we built upon? Because everything started there.”

He added: “So for me, this is really about saying, they believed in something that I don’t know why they believed – that if we could capture some of that essence, what could we do?”

Bunch, who began his career at the Smithsonian in 1978 and became its first Black secretary in 2019, insisted that museum curation must be grounded in independent scholarship rather than political pressure.

“You cannot understand the greatness of a country without understanding the totality of a country,” he said. “You cannot understand all without illuminating the dark corners. Curating means let’s shine the light. Let’s tell the truth.”

The White House has accused cultural institutions of seeking to “rewrite our Nation’s history” and ordered that warning signs be placed outside the nearby National Museum of American History. Trump has also threatened to demolish the John F Kennedy Center for the Performing Arts in Washington after a judge ruled that he could not attach his name to it.

The departing Bunch sought to assure his audience that the African American museum would endure. He said: “Every time I walk through this museum, especially on days when I was feeling like everybody was beating me up … ”

Moderator Laura Coates, a CNN anchor, interjected: “Did that happen recently?”

Bunch quipped: “Just once or twice. But I walk through and I go down and see Emmett Till’s casket and I find myself saying: ‘You can persevere.’ So for me, this is what makes me believe everything is possible. This is what makes me believe that, no matter what anybody says, you could never erase what’s in this building.”

He called the museum a “beacon of possibility” and a “place of resistance”, adding: “What I’m proudest of is that, though there’ll be pushes and attempts to try to do things, this museum will stand as long as there’s an America.”

The discussion also featured Shonda Rhimes, a television producer and board member, who pledged $1m to a newly launched legacy fund in Bunch’s honour, which was seeded by a $3.5m anonymous donation and a minimum goal of $10m.

Acting museum director Shanita Brackett said the fund will “support this museum uniquely and solely”, adding: “It will help to ensure that we continue to reflect the values of inclusion, public engagement and independent scholarship without influence.”

The Smithsonian Institution operates outside the executive branch under a board of regents that includes supreme court chief justice John Roberts and vice-president JD Vance.

After Bunch’s announcement that he was stepping down, Democratic senator Alex Padilla praised him for speaking “truth to power” in the face of Trump’s attacks, while the Heritage Foundation, a conservative thinktank, pledged to ensure Bunch’s successor did not treat the institution as a “culture-war battleground”.