Transcript for UK to expel 23 Russian diplomats, Theresa May says

Mr. speaker on Monday I set out mr. script got on his daughter we'll poisoned with and not we talk a minute to greatness agents developed by Russian. Based on this capability. Combined with that red coat of conducting state sponsored assassinations. Including against former intelligence officers who David gaunt as legitimate targets. The UK government concluded that it was highly likely that Russia was responsible for this reckless and despicable act. I was there were only two multiple explanations. I though this was a direct tax by the Russian state against our country. Or conceivably the Russian government could have lost control of the military graves met agent and allowed to get into the hands of others. Mr. speaker it was right to offer Russia the opportunity to provide an explanation. But that response has demonstrated complete disdain for the gravity as these events. They have provided to no credible explanation that they thought could suggest they lost control but then nerve agent. No explanation as to how this agent came to be used in the United Kingdom. No explanation. As to why Russia hasn't come declared chemical weapons program in contravention of international at all. Instead they have treated the use of a military graves met agent in Europe with sarcasm content and defiance. Sin is to speak that is no alternative conclusion. Other than that the Russian state was culpable for the attempted motor at missed a script and his daughter. I'm for threatening the lives of other British citizens in Seoul spring including detective Sargent nick baby. This represents an unlawful use of force by the Russian states against the United Kingdom. And as I set out on Monday it has taken place against the backdrop of a well established pattern. Of Russian state aggression across Europe and beyond. It must that will be met with a full and robust response. Beyond the actions we have already taken since the murder of mr. ditching hadn't had. I'm to counter this passion of Russian aggression house plan. As a discussion in this house on Monday made yet. It is essential that we now come to get caught with our allies to defend our security. To stand up from thousands. And to send a clear message to those who would seek to undermine them.

This transcript has been automatically generated and may not be 100% accurate.