THE leaders of America, France, and Germany have offered their support to Theresa May in her fight with Russia over the nerve agent chemical attack in Salisbury earlier this month.

In an unambiguous joint statement, the French President, Emmanuel Macron, German Chancellor, Angela Merkel, and American commander-in-chief Donald Trump say they believe Russia is responsible for the attempted murder of Sergei and Yulia Skripal.

The note from the leaders says the 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” and should be regarded as an attack on the UK’s sovereignty.

READ MORE: Nicola Sturgeon says Scotland is prepared for Salisbury-like attack

They “call on Russia to address all questions related to the attack in Salisbury” and in particular “provide full and complete disclosure of the Novichok programme to the Organisation for the Prohibition of Chemical Weapons”.

“Our concerns are also heightened against the background of a pattern of earlier irresponsible Russian behaviour. We call on Russia to live up to its responsibilities as a member of the UN Security Council to uphold international peace and security.”

The strongly worded statement, also signed by May, and released by Downing Street, follows initially weak enthusiasm for the row from France and the US.

Last week, the White House refused to say whether they thought the Russians were involved, and just two days ago, Macron’s spokesman said it was too early for France to take a position on the affair.

“We don’t do fantasy politics. Once the elements are proven, then the time will come for decisions to be made,” the spokesman said.

Yesterday Macron told to the Reuters news agency he had little doubt in his mind: “Everything leads us to believe that responsibility is in fact attributable to Russia.”

In the States, Trump, for the first time since he took office last year, took punitive action against the Russians.

Five Russian organisations, and 19 individuals were banned from entering the US, and had any assets in the country frozen.

Crucially, the US sanctions mean no American business or individual can work with a Russian firm.

During a visit to Salisbury on Thursday, May said: “We do hold Russia culpable for this brazen and despicable act that has taken place on the streets of what is such a remarkable city.

“This happened in the UK, but it could have happened anywhere and we are taking a united stance against it.”

The Russian foreign minister, Sergei Lavrov, confirmed that Moscow would soon expel British diplomats from the country in a tit-for-tat response to May’s decision to throw out 23 suspected Russian spies.

Dmitry Peskov, President Vladimir Putin’s spokesman, told reporters yesterday: “Proposals [for retaliation] will be worked out by the Foreign Ministry and other agencies, but it is indeed the president who will make the final decision.”

He said the British accusations were “baseless”.

Meanwhile, Labour leader Jeremy Corbyn appeared to toughen up his position on the row.

On Wednesday, Corbyn had appeared to suggest there was a possibility Russia might not be behind the attack.

But yesterday, he was unequivocal: “The evidence points towards Russia on this, therefore responsibility must be borne by those that made the weapon, those that brought the weapon into the country and those that used the weapon.”

He added: “The international chemical weapons convention must be invoked and the source of this weapon, which appears to be Russia either from the state or from a rogue element of the state, must be brought to justice as a result of it.

“This is a very serious issue and has to be dealt with. I made that very clear yesterday.”

Corbyn defended his approach in the Commons, saying: “What I was asking was questions, questions about the identity of the weapon, questions about the reference to the weapons convention and also the support of other allies. That’s what oppositions are there for.”

In an odd moment, Defence Secretary Gavin Williamson, often touted as a possible contender for May’s job when she stands down, seemed to channel Frank Spencer, when he told journalists Russia should “go away and shut up”.

“It is absolutely atrocious and outrageous what Russia did,” he said.