Is there a plague outbreak in Russia? If the answer were a clear yes, there shouldn’t be much reason to worry. With swift medical intervention, plague is treatable. But in the nearly three weeks since a worker at a Siberian plague research unit died of a mysterious respiratory illness, state officials have been consistently tight-lipped about what happened and whether there were any further cases.

It is this uncertainty that has the World Health Organization (WHO) and international community worried: partly because there is a – very small – risk of an outbreak, and partly because it is yet another warning that the international coordination we rely on to prevent pandemics is fraying along with the rest of international politics, and could easily fail to protect us in the future.

The key to containing an outbreak is quick disclosure and open sharing of information. Russia reportedly held high-level meetings about the case, quarantined the hospital where the worker was treated and traced about 200 contacts. That response suggests officials believed the infection was plague, and yet they did not report any of this to the WHO, as international law requires. Russia later revealed that the worker died of a pneumonia of unknown origin – hardly useful information. It undoubtedly gathered lab results and genetic sequences that could shed more light on the case, but has not shared them.

Earlier this year, the hantavirus outbreak originating on the MV Hondius cruise ship was successfully contained, showing that the global health system can still work well when countries cooperate. This latest incident suggests that one recalcitrant nation can jeopardise everyone’s safety. It is not the WHO’s fault that Russia is essentially a rogue state, but the body must be ready for such eventualities. International politics is fragmented, and only becoming more so.

Earlier this year the US left the WHO (though it is still party to some of its treaties). States follow international laws when they believe in them, or when they believe that there will be penalties – reputational or otherwise – for not playing along. The WHO has not attempted to play hardball with Russia, or set off a round of international condemnation from leading member states. Some might be heartened that on 7 October the US state department officially requested that the Russian government share information with the WHO.

However, it is likely that this reflects Washington’s increasingly ad hoc approach to international politics – using every lever available as situations arise – rather than a renewed commitment to international law. President Trump said on the same day that he would speak to Vladimir Putin about the issue. If that happened, no one has heard about it or what information may have been revealed.

The keen US interest may give credence to speculation that what in fact happened was some kind of bioweapons research leak. This is thought to be unlikely, but not impossible. The fact that such a scenario can even be plausibly entertained three weeks after the initial event speaks to a serious breakdown in the system. Western states probably do not hold much sway with Russia. But the other Brics nations may have more. The WHO used to rely on US backing for its requests. It may now have to find support among wider, more multipolar coalitions. This potential outbreak may come to nothing, but there will be another soon.