A display of Israeli and American flags at Northwestern University was vandalized with red paint Sunday night, according to the university.

The flags, along with signs and banners, had been placed on Deering Meadow, where a pro-Palestinian encampment stood for five days before organizers reached an agreement with university administration.

Northwestern University president Michael Schill said that if the vandals were Northwestern students, that disciplinary action would be pursued, though university police would be investigating.

“Let me be clear — spraying red paint over Israeli or American flags is vandalism and is unacceptable,” Schill wrote in a statement Monday. “The University will investigate these incidents thoroughly.”

Rep. Virginia Foxx (R-NC), the Republican chairperson of the U.S. House Committee on Education and the Workforce, accused the university of a “persistent failure in addressing antisemitism” in a letter sent to the school along with a request for documents and information regarding the encampment, which cleared out April 29 after a deal was struck between protesters and the university.

The school has until Friday to respond ahead of a May 23 hearing in Washington where Schill and the presidents of UCLA and Rutgers will appear in front of the committee.

The deal has spurred a lawsuit by three anonymous Northwestern students who claim the encampment subjected them to harassment.