UK Prime Minister Theresa May and Foreign Secretary Boris Johnson spent yesterday seeking support for international action against Russia.

The diplomatic offensive followed May’s declaration Monday of an ultimatum, ending midnight yesterday, for Moscow to account for the use of the Novichok nerve agent in the attempted assassination of double agent Serge Skripal in Salisbury.

May’s statements are a high-stakes effort to turn the tide internationally towards stepped-up conflict with Russia, up to and including a military confrontation. Her actions will have been coordinated with leading figures within the US military and security agencies.

Striking confirmation came when Johnson began Tuesday citing US Secretary of State Rex Tillerson’s declaration that the attack on Sergei and Yulia Skripal “clearly came from Russia” and would have consequences. This was a stronger statement than May’s official line that Kremlin involvement was “highly likely.”

Hours later, Trump announced that Tillerson had been fired and replaced by CIA Director Mike Pompeo. Tillerson’s last act was to voice his concerns over the “troubling behaviour and actions” of Russia.

Trump afterwards said he would speak to May, adding, “It sounds to me like they believe it was Russia.” He would “certainly take that finding as fact,” he said, before adding the caveat, “If we get the facts straight we will condemn Russia, or whoever it might be.”

Johnson cited a list of world leaders who have responded positively to the UK’s bellicose ultimatum: French President Emmanuel Macron, his Foreign Minister Jean-Yves Le Drian, NATO Secretary General Jens Stoltenberg, European Parliament President Guy Verhofstadt, and European Commission Vice President Frans Timmermans.

Macron spoke to May by telephone Monday night, offering full solidarity and pledging to “coordinate closely” on the UK’s agreed response. Verhofstadt, the European Parliament’s Brexit coordinator, called for EU leaders to agree “countermeasures” against Russia at a European Council summit next week, declaring the attack had taken place on what was “still European soil… We need a common European response to this outrage.”

However, Germany’s Chancellor Angela Merkel made no personal statement and her office only issued a supportive official response in the evening. Merkel “condemned the attack in the strongest possible way and assured that she took the British government’s assessment on the issue of Russian involvement extremely seriously,” the statement read. “It is up to Russia to provide swift answers to the justified questions of the British government, and comply with the request to comprehensively and promptly disclose the relevant chemical weapons programme to the Organization for the Prohibition of Chemical Weapons (OPCW).”

Germany has extensive economic ties with Russia and has opposed any escalation of sanctions, especially given Trump’s threats of trade war measures. As May was making her parliamentary address Monday, Merkel was being asked by reporters covering her Grand Coalition with the Social Democrats to comment on relations with Russia. Relaxing Russian sanctions could be “discussed,” she explained, if there was “qualitative progress” in eastern Ukraine.

So far, no EU member state has committed itself to further sanctions against Russia should May declare the state acted unlawfully on British soil. Speculation is widespread that the best outcome, given Brexit and divisions within Europe over how best to engage with Russia, would be an agreement to maintain existing sanctions.

NATO support is complicated not only by uncertainty over how Trump will react, but also by Turkey, which has emerged in recent months as a key Russian ally in the Syrian conflict.

However, media reports indicated that the UK was seeking NATO help under Article 5 of the treaty on common defence. This forced May’s housing minister, Dominic Raab, to insist that she had “chose[n] her words very carefully” by referring to an “unlawful use of force, which has a different meaning in international law to an armed attack.”

Many other avenues have been suggested for a possible UK response, including expelling diplomats and non-participation in the forthcoming World Cup in Moscow. But Syria, and stiffening international resolve for military confrontation, especially in Europe, is a key goal of May’s political scheming.

Porton Down’s “identification” of the nerve agent Novichok is not only meant to finger Russia as the guilty party—the agent was developed initially by the Soviet Union—but to raise the possibility of international action against Moscow for a war crime involving chemical weapons.

The UK has been in discussion with the OPCW since May’s speech. Its director, Ahmet Üzümcü, opened a meeting yesterday of its executive council, covering 192 member states, describing “use of a nerve agent in the United Kingdom of Great Britain and Northern Ireland” as “of serious concern… Those found responsible for this use must be held accountable for their actions.”

It is possible that Britain will ask for an OPCW investigation of Russia as an alternative means of seeking international support. Johnson said Tuesday that if Russia came up with “a convincing explanation, then obviously we will want to see full disclosure of that to the Organisation for the Prohibition of Chemical Weapons in The Hague.”

Russia’s ambassador to the OPCW, Alexander Shulgin, accused the UK of making “unfounded accusations,” “pumping hysteria” and breaching international protocols. Shulgin dismissed May’s ultimatum, urging a return to “the legal field of the chemical convention”. OPCW rules would provide a window of 10 days for Russia to respond to UK accusations of a chemical attack, Shulgin explained. “In this regard, the ultimatum demands to provide information immediately are absolutely unacceptable.”

Russian Foreign Minister Sergei Lavrov said Moscow had requested access to the substance used in Salisbury to perform its own checks, but the UK had refused and could be violating the chemical weapons convention. “Russia is not responsible,” he said. “Russia is ready to cooperate in accordance with the convention to ban chemical weapons if the United Kingdom will deign to fulfil its obligations according to the same convention.”

The Russian foreign ministry summoned the UK’s ambassador Laurie Bristow to Moscow for talks with Vladimir Titov, first deputy minister for foreign affairs.

Elsewhere, Nikolay Kovalev, a former director of Russia’s Federal Security Service, the FSB, suggested that British intelligence agencies were complicit in the attempt on the life of Skripal.

The only beneficiaries from Skripal’s poisoning were the US and the UK, he stressed. Defectors “are fully under surveillance … the secret services are monitoring them, they know their whereabouts and schedules. And then you have such strange events happen in a row.”

The British “scapegoat this or that traitor after having utilized him to the maximum extent, and then say the Russians did it.”

Novichok nerve agents “were stockpiled in former Soviet Union republics—sorry, but Ukrainian involvement can’t be ruled out,” he said. General Vladimir Mikhailov, a former high-ranking FSB officer, told RIA Novosti that MI6 “could have synthesized the agent and use it for political purposes.”

In the UK, Home Secretary Amber Rudd embraced an initiative led by Blairite Yvette Cooper, Labour chair of the Commons home affairs committee, who wrote to Rudd asking for an investigation into 14 Russian deaths in the UK that have not been treated as suspicious by the police.

The Metropolitan police counter-terrorism command also announced that it was investigating the death of Nikolai Glushkov, 68, a close friend of the late oligarch and Putin opponent Boris Berezovsky.

Glushkov was found dead in his London home Monday night. The Met said the counter-terrorism command unit was involved “as a precaution because of associations that the man is believed to have had” and that there was no evidence of a link to events in Salisbury.