Changes at the Smithsonian, a longstanding American institution, have both staffers and historians concerned, according to new reports. Here’s a timeline of what has been going on.

In a letter addressed to Lonnie G. Bunch III, the Secretary of the Smithsonian, White House officials said they would lead a “comprehensive internal review” of Smithsonian museums and exhibitions, focusing on areas including public-facing content, the curatorial process, and exhibition planning, among others.

The White House is conducting a comprehensive internal review of exhibits and materials at the Smithsonian Institution in an effort to comply with President Donald Trump’s directive about what should and shouldn’t be displayed.