Russia on Tuesday urged the United States not to take military action against Bashar al-Assad’s regime in Syria in response to an alleged chemical attack in the rebel-held city of Douma, the BBC reported.

“I would once again beseech you to refrain from the plans that you’re currently developing,” Moscow’s envoy to the United Nations, Vasily Nebenzia, told the US. He warned the Donald Trump administration that it would bear responsibility for any “illegal military adventure” in Syria.

Responding to Russia’s message, US President Donald Trump asked the country not to support Syria. “Russia vows to shoot down any and all missiles fired at Syria,” Trump said on Twitter. “Get ready Russia, because they will be coming, nice and new and smart! You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!”

In another tweet, Trump said Washington’s relationship with Moscow was worse that it has ever been, including the Cold War. “There is no reason for this. Russia needs us to help with their economy, something that would be very east to do, and we need all nations to work together. Stop the arms race?”

Russia said the missiles that the US president promised to send to Syria would destroy evidence of suspected chemical attack, reported AP.

Trump and British Prime Minister Theresa May have called for action against Assad and his supporters in the aftermath of the attack. The US Ambassador to the UN, Nikki Haley, accused Russia of having the “blood of Syrian children” on its hands. French President Emmanuel Macron has also said that if strikes are ordered, they would target the Syrian government’s chemical facilities.

At least 500 people showed symptoms of chemical attack: WHO

The World Health Organization on Wednesday demanded unhindered access to Douma to provide medical attention to those affected, BBC reported. WHO said its medical partners in the area reported that nearly 500 people had shown symptoms of being exposed to toxic chemicals, including difficulty in breathing, irritation of mucous membranes and disruption in the central nervous system.

“We should all be outraged at these horrific reports and images from Douma,” said Dr Peter Salama of the organisations. “WHO demands immediate unhindered access to the area to provide care to those affected, to assess the health impacts, and to deliver a comprehensive public health response.”

Russia on Tuesday vetoed a US-drafted United Nations Security Council resolution that sought to set up a committee to investigate the alleged attack, AFP reported. It was the 12th time that Kremlin used its veto power to a stop a resolution targeting the Assad regime. “We are using the veto in order to protect international rule of law, peace and security, to make sure that you do not drag the Security Council into your adventures,” Nebenzia claimed. A resolution drafted by Russia also failed to garner enough support.

The Organisation for the Prohibition of Chemical Weapons on Tuesday announced that it would deploy a fact-finding team to investigate the allegations.