We, the leaders of France, Germany, the United States and the United Kingdom, abhor the attack that took place against Sergei and Yulia Skripal in Salisbury, United Kingdom, on March 4, 2018. A British police officer who was also exposed in the attack remains seriously ill, and the lives of many innocent British citizens have been threatened. We express our sympathies to them all, and our admiration for the United Kingdom police and emergency services for their courageous response. This use of a military-grade nerve agent, of a type developed by Russia, constitutes the first offensive use of a nerve agent in Europe since the Second World War. It is an assault on the United Kingdom’s sovereignty and any such use by a state party is a clear violation of the Chemical Weapons Convention and a breach of international law. It threatens the security of us all. The United Kingdom thoroughly briefed its allies that it was highly likely that Russia was responsible for the attack. We share the United Kingdom’s assessment that there is no plausible alternative explanation, and note that Russia´s failure to address the legitimate request by the government of the United Kingdom further underlines Russia’s responsibility. We call on Russia to address all questions related to the attack in Salisbury. Russia should, in particular, provide full and complete disclosure of the Novichok program to the Organisation for the Prohibition of Chemical Weapons (OPCW). Our concerns are also heightened against the background of a pattern of earlier irresponsible Russian behavior. We call on Russia to live up to its responsibilities as a member of the U.N. Security Council to uphold international peace and security.