Theresa May has provided a clear basis for the UK government’s conclusion that former Russian intelligence agent Sergei Skripal and his daughter were poisoned with Novichok, a military-grade nerve agent developed by Russia. As Prime Minister May has said, Russia has provided no credible explanation in response, but instead has treated the use of a Russian-developed chemical weapon in Europe with disdain.

This is obviously an event that the UK government needs to respond to seriously and proportionately. But it’s bigger than just a UK–Russia dispute, and bigger than an attempted murder investigation. It’s a test of whether it’s becoming acceptable to use one of the most horrific types of weapons—chemical weapons—that humanity has ever produced without there being international consequences for those who use those weapons.

Just over 20 years ago, the Chemical Weapons Convention came into force. It’s hard to get the international community to agree on anything, but 192 states signed and ratified the convention because of the simple, horrific and indiscriminate suffering that chemical weapons inflict on human beings. The signatories agreed that such weapons were too horrific to use.

As the Organisation for the Prohibition of Chemical Weapons (OPCW) says, chemical weapons—think poison arrows, boiling tar and arsenic smoke—have been used as tools of war for thousands of years. The scale of death, destruction and long-term human misery that chemical weapons inflicted during World War I was so graphic, however, that few countries wanted to be the first to use such weapons again. By the end of World War I, chemical weapons had caused some 90,000 deaths and more than one million casualties. The wounded suffered the effects for the rest of their lives.

That’s why enforcement of the Chemical Weapons Convention is so important to all states. The convention had its genesis because of chemical weapons used in war. We’re now seeing chemical weapons used during peace.

Russia is a signatory to the convention. It declared in September 2017 that it had completed the destruction of its 40,000 tonnes of chemical weapons. It didn’t declare Novichok, which we now know that it possessed—despite states being obliged to declare all chemical weapons programs and holdings. The US expressed doubt that Russia had actually complied with its obligations under the convention. This looks to be correct.

Russia is the inventor of the Novichok chemical weapon, as confirmed by one of the program scientists, Vil Mirzanyanov. Sergei Skripal, the target of the Salisbury attack, is a former Russian intelligence agent who worked for the UK. So, as Prime Minister May has said, it seems Russia is the only party with the particular capability used to attack Mr Skripal. And Russia had the only motive for doing so.

The Russian foreign ministry’s denials are implausible. But implausible denials have the Alice in Wonderland effect of protecting Russia from accountability. This is an example of Vladimir Putin’s hybrid warfare, or probably what’s better described as ‘hybrid politics’. He’s willing to use Russian power in transparent ways and trust that responses will be ineffective or require long processes that he can frustrate.

So, what’s to be done?

The initial Russian response to the UK’s request for an explanation has been to deny any knowledge or involvement, and to request more details. Russian spokespeople have also started to provide ‘alternative facts’ about the attack, even speculating that it could have been conducted by UK authorities to discredit Russia.

The predictable result is that the UK is expelling a number of Russians. The Russians will reciprocate. Time will then pass and relations will be resumed. Prime Minister May has also foreshadowed freezing Russian state assets in the UK and passing legislation to allow more UK sanctions on human rights grounds. She has noted the importance of cooperation with partners, singling out France, Germany and the United States. All of that is to the good.

Formal steps can be taken by the UK to request assistance from the OPCW to investigate Russia. The OPCW can conduct ‘challenge inspections’ of Russian facilities it suspects of holding or making the chemical weapon. Russia’s 2017 declaration of compliance with the convention can be challenged based on the new information from the Salisbury attack.

Russia has said it will cooperate with investigations, but insists that the UK provide it with all of the evidence that it has.

Russia will probably continue to declare its willingness to comply while disputing any evidence and obstructing any actual investigation. It has done the same in the investigation into the shooting down of Malaysian Airlines flight MH-17. That shouldn’t stop the UK from using all the investigatory and verification measures in the Chemical Weapons Convention to pursue Russian behaviour. The UK should do so with the vocal support of other convention signatories.

While frustrating and lengthy, these steps are the essential, formal steps needed to reinforce the international prohibition on the use of chemical weapons.

The actions most likely to matter to decision-makers in the Kremlin are those that affect their quality of life as individuals. So, Russia can also be the subject of multilateral and unilateral sanctions.

Given Mr Putin’s tight control over the state security agencies and his strong dislike of betrayal of the Russian homeland, it seems unlikely that a decision to use Novichok abroad would be a decision made anywhere in Russia except in the Kremlin.

Russian elites have benefitted from holding assets abroad. These include real estate in London, New York and Paris. They have bank accounts and stock holdings in UK banks and other Western institutions. Luxury yachts are among the kinds of assets that matter to elites who are part of Kremlin policymaking—notably members of Russia’s National Security Council and close advisers to President Putin.

Preventing Russian leadership figures from enjoying the benefits of assets held overseas will matter in a way that stern reprimands and reciprocal expulsions of diplomats and spies won’t. Sanctions can prevent the same people from travelling.

So, it’s not enough to leave action to the UK government when what’s at stake is the normalisation of the use of chemical weapons. Every government that’s a party to the Chemical Weapons Convention, including Australia, has a role in promoting and taking action. Australia has additional interests as a close partner of the UK.

Let’s see our government take the steps necessary–including cooperation with our partners on sanctions–to help prevent chemical weapon attacks from becoming business as usual.