With permission, Mr Speaker, I would like to update the House on the incident in Salisbury and the steps we are taking to investigate what happened and to respond to this reckless and despicable act.

Last week, my right hon. Friends the Foreign and Home Secretaries set out the details of events as they unfolded on Sunday 4 March. I am sure that the whole House will want to pay tribute again to the bravery and professionalism of our emergency services and armed forces in responding to this incident, as well as the doctors and nurses who are now treating those affected. In particular, our thoughts are with Detective Sergeant Nick Bailey, who remains in a serious but stable condition. In responding to this incident, he exemplified the duty and courage that define our emergency services and in which our whole nation takes the greatest pride.

I want to pay tribute to the fortitude and calmness with which people in Salisbury have responded to these events and to thank all those who have come forward to assist the police with their investigation. The incident has, of course, caused considerable concern across the community. Following the discovery of traces of nerve agent in a Zizzi restaurant and the Mill pub, the chief medical officer issued further precautionary advice, but, as Public Health England has made clear, the risk to public health is low.

I share the impatience of the House and the country at large to bring those responsible to justice and to take the full range of appropriate responses against those who would act against our country in this way. But as a nation that believes in justice and the rule of law, it is essential that we proceed in the right way, led not by speculation but by the evidence. That is why we have given the police the space and time to carry out their investigation properly. Hundreds of officers have been working around the clock, together with experts from our armed forces, to sift and assess all the available evidence, to identify crime scenes and decontamination sites and to follow every possible lead to find those responsible. That investigation continues and we must allow the police to continue with their work.

This morning, I chaired a meeting of the National Security Council in which we considered the information available so far. As is normal, the council was updated on the assessment and intelligence picture, as well as on the state of the investigation. It is now clear that Mr Skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by Russia. It is part of a group of nerve agents known as Novichok.

Based on the positive identification of this chemical agent by world-leading experts at the Defence Science and Technology Laboratory at Porton Down, our knowledge that Russia has previously produced this agent and would still be capable of doing so, Russia’s record of conducting state-sponsored assassinations and our assessment that Russia views some defectors as legitimate targets for assassinations, the Government have concluded that it is highly likely that Russia was responsible for the act against Sergei and Yulia Skripal. There are, therefore, only two plausible explanations for what happened in Salisbury on 4 March: either this was a direct act by the Russian state against our country; or the Russian Government lost control of their potentially catastrophically damaging nerve agent and allowed it to get into the hands of others.

This afternoon, my right hon. Friend the Foreign Secretary has summoned the Russian ambassador to the Foreign and Commonwealth Office and asked him to explain which of the two possibilities it is and to account for how this Russian-produced nerve agent could have been deployed in Salisbury against Mr Skripal and his daughter. My right hon. Friend has stated to the ambassador that the Russian Federation must immediately provide full and complete disclosure of the Novichok programme to the Organisation for the Prohibition of Chemical Weapons, and he has requested the Russian Government’s response by the end of tomorrow.

This action has happened against a backdrop of a well-established pattern of Russian state aggression. Russia’s illegal annexation of Crimea was the first time since the second world war that one sovereign nation has forcibly taken territory from another in Europe. Russia has fomented conflict in the Donbass, repeatedly violated the national airspace of several European countries and mounted a sustained campaign of cyber-espionage and disruption, which has included meddling in elections and hacking the Danish Ministry of Defence and the Bundestag, among many others.

During his recent state of the union address, President Putin showed video graphics of missile launches, flight trajectories and explosions, including the modelling of attacks on the United States with a series of warheads impacting in Florida. The extra-judicial killing of terrorists and dissidents outside Russia was given legal sanction by the Russian Parliament in 2006, and, of course, Russia used radiological substances in its barbaric assault on Mr Litvinenko. We saw promises to assist the investigation then, but they resulted in denial and obfuscation and the stifling of due process and the rule of law.

Following Mr Litvinenko’s death, we expelled Russian diplomats, suspended security co-operation, broke off bilateral plans on visas, froze the assets of the suspects and put them on international extradition lists, and those measures remain in place. Furthermore, our commitment to collective defence and security through NATO remains as strong as ever in the face of Russian behaviour. Indeed, our armed forces have a leading role in NATO’s enhanced forward presence, with British troops leading a multinational battlegroup in Estonia. We have led the way in securing tough sanctions against the Russian economy, and we have at all stages worked closely with our allies and will continue to do so. We must now stand ready to take much more extensive measures.

On Wednesday, we will consider in detail the response from the Russian state. Should there be no credible response, we will conclude that this action amounts to an unlawful use of force by the Russian state against the United Kingdom, and I will come back to this House to set out the full range of measures that we will take in response.

This attempted murder using a weapons-grade nerve agent in a British town was not just a crime against the Skripals, but an indiscriminate and reckless act against the United Kingdom, putting the lives of innocent civilians at risk. We will not tolerate such a brazen attempt to murder innocent civilians on our soil. I commend this statement to the House.