Russia is emboldened by US reluctance to act decisively

One fear is that as things go badly on some fronts in Ukraine, she will use such weapons to turn the tide. It is US and NATO policy to deter a chemical attack by threats of punishment. For deterrence to work, Moscow must believe that Washington will act decisively.

Circumstances in Ukraine pose deterrence challenges, with the US already nearing the limit of what action it can take against Russia, other than direct attack (which President Joe Biden ruled out). It imposed crushing sanctions and last week increased the volume of arms sales to Ukraine.

It is unclear whether the remaining threats are significant enough to cause Russia to reconsider. There are still economic measures that could be imposed, such as US sanctions on more financial firms or a European embargo on Russian oil and gas.

NATO has probably not exhausted all possibilities of arms support. Germany, for example, has discussed sending Leopard main battle tanks. But the deterrent value of these measures is questionable. The Russian leadership has likely factored in tougher economic penalties after long telling its people sanctions are inevitable.

It also seems unlikely that the prospect of additional NATO arms deliveries to Kyiv will figure prominently in Moscow’s calculations, given that the weapons now arriving in Ukraine are already deadly.

Russia is almost certainly not afraid of diplomatic rows over the use of chemical weapons. The OPCW has procedures in place to investigate chemical attacks, as it did in Syria, where it has repeatedly found the Syrian government responsible. But any meaningful consequences for a chemical weapons attack in Ukraine would fall victim to Russia’s veto in the UN Security Council.

International shaming would not be effective either. Russia’s diplomatic and disinformation shielding of the Assad government and its assassination attempts using Novichok agents suggest it is immune to efforts to tarnish its international image. Their troops are already being accused of heinous atrocities in Ukraine.

The case of Syria shows that deterrence can be a challenge even in cases that do not directly involve a nuclear power. President Barack Obama’s 2012 warning that the use of chemical weapons was a “red line” did not stop Syrian forces from using sarin to kill more than 1,400 people a year later, in August 2013.

The US did not strike in retaliation. Instead, it negotiated a deal with Russia to remove and destroy all remaining chemical weapons. But Syrian President Bashar al-Assad continued his attacks, implying that the US failure to respond to the initial deterrence failure in 2013 had undermined American credibility.

In April 2017 and April 2018, the Trump administration attempted to restore deterrence by launching missile attacks on Syria following renewed chemical attacks. But Damascus and Moscow appear to have dismissed the strikes as one-off actions.

The Syrian case suggests that stopping a motivated actor from using chemicals is difficult, especially when the deterrent side does not react decisively to crossing the “red line”.

Regarding Ukraine, the Biden administration has warned Moscow of an unspecified “in-kind” response to chemical use that could involve either military action or some form of asymmetric action — such as a cyberattack on Minsk.

Still, Washington’s reasonable reluctance to engage in direct conflict with Russia would likely dictate reluctance to choose such a response.

The challenge in responding to a Russian chemical weapons attack is that the punitive toolkit includes the very deterrents that have failed to change Moscow’s calculus at all.

While Russia’s position in the UN Security Council makes sanctions based on an OPCW investigation unlikely, such an investigation would not be entirely pointless.