An interesting situation is developing at the OPCW – the global chemical weapons watchdog – regarding Syria and Russia.

Last July the OPCW's executive council set a 90-day deadline for Syria to provide further information about its chemical weapons programme – some of which it was supposed to have provided seven years ago.

The deadline expires tomorrow (October 7) and in the likely event that Syria fails to comply the OPCW will then face the question of what to do about it.

Syria joined the Chemical Weapons Convention under international pressure in 2013 following a nerve agent attack in Ghouta that killed hundreds. On joining the convention Syria 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 OPCW supervision.

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).

● Syria and chemical weapons
A compilation of blog posts and documents looking at the arguments and the evidence

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 is 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.

Those findings came from the recently constituted Investigation and Identification Team (IIT) which Syria, despite being bound by OPCW rules, refuses to recognise or cooperate with.

Syria denies ever using chemical weapons (despite abundant evidence to the contrary) and instead blames rebel fighters even though most chemical attacks have hit rebel-held territory. It is supported in this by its chief ally, Russia, which has been running a lengthy campaign to discredit the OPCW and its investigators.

Last week, in apparent anticipation of the October deadline expiring, Russia sponsored an Arria-formula meeting at the UN security council where critics of the OPCW were given a platform via video links. Speakers included Ian Henderson, a disaffected former OPCW inspector, Aaron Maté from The Grayzone (an "alternative" website), and Theodore Postol, an emeritus professor at Massachusetts Institute of Technology who disputes many of the OPCW's findings in relation to Syria.

The US and others on the security council have dismissed this as a Russian propaganda stunt. Henderson previously appeared at a similar meeting targeting the OPCW last January, along with Syrian and Russian speakers.

In the meantime, relations between the OPCW and Russia have been further complicated by the chemical attack on Alexei Navalny in August. Navalny, a Russian opposition figure, was poisoned on Russian territory and the Russian security apparatus is the most obvious suspect.

Navalny, who survived the attack, was initially treated in a Russian hospital and later allowed to continue his treatment in Germany. The German government has since claimed to have "unequivocal proof" that he was poisoned with a Novichok-type nerve agent. The Russians, however, say samples taken from Navalny before he left the country showed no evidence of a nerve agent.

Novichok was previously used for the 2018 attack on former Russian spy Sergei Skripal and his daughter in Britain – an attack in which two Russian GRU operatives were the main suspects.

Russia has since proposed "consultations" with Germany about the Navalny affair, including a request for biological and clinical samples. It has also asked the OPCW to "cooperate" with Russian experts in studying samples. The organisation is currently awaiting the results of its own analysis and says it will pass them to Germany (rather than Russia) when they become available.

Russia's ostensible desire for cooperation is at odds with its repeated denunciations of the OPCW and should probably not be taken at face value. On Monday, in what appeared to be a tongue-in-cheek reference to this contradictory stance, director-general Fernando Arias thanked Russia "for its trust" in the OPCW's "independence and expertise". 

Arias also assured Russia that the OPCW was ready to assist but asked for "further clarification" about what is proposed.

Separately, Germany has raised questions about the legal basis for Russia's proposed consultations. Russia based its request on Article IX, paragraph 2, of the Chemical Weapons Convention but Germany points out that this only relates to "any matter which may cause doubt about compliance with this Convention, or which gives rise to concerns about a related matter which may be considered ambiguous" and is thus not relevant to the Russian request.

Germany has also informed Russia that under German privacy law it would not be able to disclose Navalny's medical records without his consent.

These responses from Germany and the OPCW suggest there could be a long period of wrangling over the nature and terms of any cooperation with Russia in the Navalny affair.

One other possible outcome might be a "challenge inspection" by the OPCW in Russia under Article IX, since Navalny's poisoning raises doubts about Russia's compliance with the Convention. Any member state is allowed to initiate such an inspection. A challenge inspection can be launched with only 12 hours' notice to the country concerned but its scope is restricted. Under the rules, the OPCW has to state in advance exactly what it wants to inspect.

Russia is unlikely to welcome that and would almost certainly step up harassment of the OPCW if it happened.