It is “highly likely” that Russia was to blame for the attack on former Russian spy Sergei Skripal and his daughter using a deadly nerve agent, British Prime Minister Theresa May told MPs. The government is now waiting for a response from Russian diplomats before formulating its response, though Russian foreign minister Sergei Lavrov has already denied the country is to blame.

But how can Britain respond to the attack in Salisbury in a way that shows the public that the government can protect national security while also being effective in the murky world of counterespionage? The options are limited and none are likely to be that effective.

Britain is currently part of the EU sanctions regime against Russia, imposed after its annexation of Crimea in 2014. These include trade and financial sanctions as well as targeted sanctions against individuals at the heart of the office of Russian president, Vladmir Putin. The impact of these sanctions on Russian government policy is, however, slim.

The attack on the Skripals bears similarities to the poisoning of Alexander Litvinenko in 2006 with the radioactive agent polonium. The government inquest into Litvinenko’s killing took nearly a decade and, in 2016 found that Putin’s office was “probably” at the heart of the decision to kill the former spy. The US and UK froze the assets of those deemed responsible for the assassination, Andrei Lugovoi and Dmitry Kovtum. American and European allies jumped forward to support the UK to protest this brazen attack.

The White House remained silent on the Skripal attack for days, but Donald Trump has now indicated that he will be talking to May about it.

The EU sanctions could go further, though the UK’s welcoming attitude to Russian finance and investment in the City of London has so far been a barrier to this. So too has the attitude of many southern EU member states who see Russia as a major investor in their economies rather than a territorial or political threat. Further action would take a major change in the way that the West seeks to counter Russia at home and abroad.

Some may argue that escalating sanctions against Russia in 2018 – particularly given the complexity of the quagmire in Syria and Russia’s role in supporting the Assad regime there – might be counterproductive. Still, the UK government is under growing pressure to do something in response to the Salisbury attack and the threat to the public health of its citizens.

In the first instance, more sanctions against Russian financial assets could be introduced that would mirror the US Magnitsky Act, which has gone further than the EU’s sanctions in targeting financial interests and corruption close to Putin and his closest advisers. Introduced in the US in 2012, the act gives the government powers to put sanctions on people suspected of human rights abuses around the world.

The problem for the UK would be coming to terms with the scale of Russian investment in the UK that would currently contravene the Magnitsky Act.

The biggest challenge, however, would be the near irrelevance of further sanctions at this stage of the contest between the West and Russia. Sanctions are more likely to work at the beginning of a conflict, and become increasingly irrelevant the longer it goes on, with the first six months of sanctions being the most effective. With sanctions against Russia in place since 2014, a new round is therefore unlikely to have much impact.

The UK could also move to counter Russian intelligence on UK soil. The goal would be to direct UK security services to make it increasingly difficult for Russian intelligence operatives to work on the ground – and more difficult to get nerve agents or other poisons into the country. This has the potential to be more successful in protecting the UK against such brazen attacks than further sanctions would, but it could stretch British security services further at a time when global jihadism and cyberattacks are already heaping pressure on counterespionage agencies. And it would be done behind closed doors, rather than as a public response to the Skripal attack.

An escalation of support for Ukraine is perhaps the most likely response even if it is not tied specifically to the Skripal attack. While current Russian military involvement in the Donbas region of Ukraine has lessened, it has continued to support the “people’s republics” in Donetsk and Lugansk through material aid and armaments. Further material aid and armaments for Ukrainian forces would be an operationally effective response from the UK – though it would not necessarily prevent another attack on the UK.

The final – and least probable response – would be a quid pro quo attack on Russian intelligence assets in Russia itself, either counterespionage or a cyber offensive. But Russia has the potential and wherewithal to escalate this tension between the West and Russia even further. Any attack on Russia itself, even if targeted at people who spied on the West – such as Anna Chapman, the Russian spy for who Skripal was swapped – would further deteriorate the UK-Russian relationship.

The most likely outcome is a combination of further sanctions, extra counterespionage as an effective tool for the British security services, and further support for Ukraine in order to agitate Russia through a proxy to avoid open escalation.

None of these activities are transformative. But perhaps neither is the Skripal attack – although the breaking of a Cold War taboo against the use of chemical weapons, suggests that the potential for further escalation is increasing. While there will be Western politicians who call for restraint against further escalation, these will be the same politicians who fail to see that Russia has transformed what some may call a Cold War into something much warmer.

This article was originally published on The Conversation 

David J Galbreath is Professor of International Security, Director of Centre for War and Technology, University of Bath