The International Criminal Court, the world’s war crimes tribunal, was hit by a cyber attack earlier this week and is still not back up and running after the incident.

The court announced in a statement on Tuesday that it had “detected anomalous activity affecting its information systems.” The website was briefly down on Sunday and staff members still do not have access to email or other software systems.

It’s unclear what, if any, information was compromised in the hack. The Hague-based court has 31 cases currently underway, many of which use witnesses whose identities are protected or rely on evidence that is shielded from public view for security reasons.

According to the NOS, “a large number of sensitive documents have been taken.”

Lawyers, defendants and judges are unable to use any of the institution’s systems off-site.

The court is currently investigating crimes in 17 countries, from the Philippines to Venezuela and operates several field offices across the world. It just opened its largest in Kyiv last week to look into the more than 100,000 possible crimes stemming from the Russian invasion.

It’s unclear when things will return to normal. Defence lawyers “do not receive any information about the possible effect of the hack on the concrete cases pending for ICC,” lawyer Geert-Jan Knoops told Dutch News.

He is currently representing Patrice-Edouard Ngaïssona, the former minister of sports for the Central African Republic. Ngaïssona is facing 32 counts of war crimes and crimes against humanity for his role in his country’s ongoing civil war.

A hearing in the case scheduled for Monday was canceled and ultimately rescheduled for Thursday. But the court did not live stream the proceedings and no audio was available in the public gallery, effectively preventing anyone but the lawyers and the judges from hearing the proceedings.

The court said it was grateful to Dutch authorities for their assistance. “Immediate measures were adopted to respond to this cybersecurity incident and to mitigate its impact,” Fadi El Abdallah, the court’s spokesperson, said in a statement. The ICC has refused to elaborate further on who might be behind the attack.

A spokesperson for the Dutch justice ministry confirmed that the National Cyber Security Centre is helping with the investigation.

The court issued an arrest warrant earlier this year for Russian President Vladimir Putin for war crimes. Prosecutors say the leader has overseen a program to kidnap Ukrainian children and bring them to Russia for “reeducation.”

Russia has tried to gain access to the court before. Last year, the Dutch security service AIVD discovered a Russian national posing as a Brazilian to get work at the court. The man, named by the AIVD as Sergey Vladimirovich Cherkasov, worked for the Russian intelligence service GRU.

He was arrested at Schiphol when he arrived in the Netherlands.

In August, the court’s chief prosecutor Karim Khan announced his office would start investigating cybercrime. “Cyber warfare does not play out in the abstract. Rather, it can have a profound impact on people’s lives,” he wrote in Foreign Policy Analytics.

It’s not clear if an attack on the ICC itself would qualify as a crime under the 2002 Rome Statute which established the court.