THE HAGUE, Netherlands (AP) — The International Criminal Court’s chief prosecutor Karim Khan made an unannounced visit to Damascus on Friday, meeting with the leader of Syria’s de facto government.

Khan’s office says he visited on the invitation of Syria’s transitional government to offer support in ensuring accountability for alleged crimes committed in the country.

Khan met with the country’s leader Ahmed al-Sharaa and the foreign minister to discuss options for justice in The Hague for the victims of the conflict, which has left more than half a million dead and more than six million people displaced.

Al-Sharaa leads Hayat Tahrir al-Sham, or HTS, the group leading the new authority in Syria. The former insurgent group led the lightning offensive that toppled longtime dictator Bashir al-Assad last month and is now the de facto ruling party in the country.

Assad, who fled to Russia in December, waged an oppressive campaign against anyone who opposed him during his more than two decades in power.

Rights groups estimate at least 150,000 people went missing after anti-government protests began in 2011, most vanishing into Assad’s prison network. Many of them were killed, either in mass executions or from torture and prison conditions. The exact number remains unknown.

The global chemical weapons watchdog found Syrian forces were responsible for multiple attacks using chlorine gas and other banned substances against civilians.

The new authorities have called for members of the Assad regime to be brought to justice. It is unclear how exactly that would work at this stage.

Syria is not a member of the ICC, which has left the court without the ability to investigate the war. In 2014, Russia and China blocked a referral by the United Nations Security Council which would have given the court jurisdiction. Similar referrals were made for Sudan and Libya.