The noose was found in an exhibit on segregation, a museum spokeswoman said. It was removed by the Park Police and the exhibit was reopened about an hour later.
In the letter, Skorton said in part, “We will not be intimidated. With new urgency, we will tell the story of our nation and all its people. We will continue to fight this sort of ignorance with knowledge. … We will remain vigilant and, in spite of these deplorable acts, we will become a stronger institution for all Americans.”
He added that counseling was available for any worker who needed it.
Last Friday, a noose was found on the grounds of the Hirshhorn Museum, another Smithsonian museum on the National Mall.
Earlier this month, two men were charged with hate crimes after a noose was found hanging from Crofton Middle School, in Maryland.
“This is history. This should not be happening in this day and age,” a visitor to the museum told NBC Washington.