British Prime Minister Theresa May says the government has concluded it is "highly likely" that Russia was responsible for the poisoning earlier this month of former Russian double agent Sergei Skripal and his daughter, Yulia.
Speaking to the House of Commons Monday, Prime Minister May also said the nerve agent used in the attack in southwest England was a military-grade substance developed by Russia.
May said: "Either this was a direct act by the Russian state against our country, or the Russian government lost control of its potentially catastrophically damaging nerve agent and allowed it to get into the hands of others. This afternoon, my right honorable friend, the foreign secretary, has summoned the Russian ambassador to the Foreign and Commonwealth office and asked him, asked him to explain which of these two possibilities it is.
"Mr. Speaker, 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 Russia state against the United Kingdom. And I will come back to this house and set out the full range of measures that we would take in response."
Russia's Foreign Ministry called May's statement a "circus show" and "provocation," according to Russian news agencies.