When the 193 countries that are parties to the Chemical Weapons Convention hold their annual meeting next week they will face a tricky question regarding one of the members.

The general assumption of the Convention is that if countries are willing to sign up to it they are also likely to comply with its provisions – so there is no real enforcement mechanism.

Syria, though, has never been a particularly willing participant. It held off joining the Convention until 2013 and did so then under international pressure after carrying out a nerve agent attack that killed hundreds.

On joining the convention Syria formally committed itself to chemical disarmament. It was required to declare all its stocks and related production facilities, which would then be destroyed or dismantled under the supervision of the Organisation for the Prohibition of Chemical Weapons (OPCW).

However, Syria's initial declaration – as the Assad regime later acknowledged – was incomplete. During the last few years numerous amendments have been made to the original document in the light of inspectors' discoveries and the OPCW has still not accepted the revised version. There remain "gaps, inconsistencies and discrepancies" (to use the official phrase).

At its July meeting the OPCW's executive council called on Syria to "resolve all of the outstanding issues" regarding its initial declaration and declare "all of the chemical weapons it currently possesses" together with related production facilities.

Syria was also required to provide information about facilities involved in a series of chemical attacks in March 2017, for which an OPCW investigation has since found "reasonable grounds" to blame the Assad regime.

The executive council set a 90-day deadline for Syria to comply with these demands but the deadline expired in October and the matter has now been passed to the Conference of the States Parties – the OPCW's governing body which comprises all countries that are parties to the Chemical Weapons Convention.

Under Article XII of the Convention, the states parties could suspend Syria's "rights and privileges" until it complies. That could include such things as withdrawal of Syria's voting rights but would probably not make the Assad regime more compliant. The regime could also retaliate by causing further difficulties for the OPCW's continuing investigations of alleged chemical attacks in Syria.

Another option would be to refer the matter to the UN Security Council but action there would almost certainly be blocked by Russia, as has happened previously.