The first batch of materials from a chemical stockpile has been removed from Syria and loaded on a Danish ship, initiating the process of transferring it for destruction, the United Nations and the Organization for the Prohibition of Chemical Weapons said Tuesday.

“A first quantity of priority chemical materials was moved from two sites to the port of Latakia for verification and was then loaded onto a Danish commercial vessel today,” Sigrid Kaag, the head of international weapons inspectors in Syria, said.

The vessel will remain at sea awaiting the arrival of additional chemical materials at the port. Maritime security is being provided by naval escorts from China, Denmark, Norway and Russia.

Syria agreed to dispose of its weapons in line with a Russian-U.S. deal, following international outrage and the threat of military strikes after hundreds died in a chemical attack on a rebel-held area outside Damascus in August.

The chemicals initially were scheduled to be removed from the country by Dec. 31, but the move was delayed because of the ongoing war.

The stockpile would be transferred later to a U.S. ship for destruction at sea. According to the plan, the priority chemicals are to be destroyed by the end of March and the entire arsenal eliminated by the end of June.