Last week, President Donald J. Trump suspended all U.S. refugee programs and banned immigration from seven Muslim-majority countries. Three of those countries are members of the African Union (AU), and the Independent reports that the AU isn’t happy about Trump’s executive order.

The head of the AU criticized the ban saying it presents “one of the greatest challenges” for the continent.

“The very country to which many of our people were taken as slaves during the transatlantic slave trade has now decided to ban refugees from some of our countries,” said Nkosazana Dlamini-Zuma.

Representatives of the union met in Addis Ababa for a two-day summit when Dlamini-Zuma made the remarks.

“The very country to which many of our people were taken as slaves during the transatlantic slave trade has now decided to ban refugees from some of our countries,” said Nkosazana Dlamini-Zuma.

Trump’s executive order prevents people with passports from travelling to the U.S. Three of the seven countries banned—Somalia, Sudan and Libya—from entering the country are African nations. It has also blocked visas from citizens from Syria, Iran, Iraq and Yemen.

“What do we do about this?, Dlamini-Zuma questioned. “Indeed, this is one of the greatest challenges to our unity and solidarity.”