President Donald Trump warned Russia Wednesday to brace for American engagement in Syria after a suspected chemical attack killed dozens of people.

“Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and ‘smart!’” Trump said on Twitter.

“You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!" he added, referring to Syria’s Bashar al-Assad.

The comments followed a warning from Moscow that a risk of a direct Russia-U.S. military clash in Syria “is higher than before”, with a Russian envoy saying that U.S. missiles flying over the war-ravaged country would be shot down.

In a second tweet, Trump said the U.S.-Russian relationship “is worse now than it has ever been”.

“There is no reason for this. Russia needs us to help with their economy, something that would be very easy to do, and we need all nations to work together. Stop the arms race?” Trump said.

He later blamed much of the deterioration in ties on a “Fake & Corrupt” special counsel probe into Russia’s alleged attempts to influence the 2016 presidential race, and the Trump campaign’s possible collusion with the effort.

The probe, he claimed in a third tweet, is being led by “Democrat loyalists, or people that worked for Obama. Mueller is most conflicted of all.”

The investigation has been a constant focus of ire for the American president, particularly after it referred a case to the Justice Department which then raided the workplace and hotel of Trump’s long-standing personal lawyer, Michael Cohen on Monday. The raids sought documents on payments to two women who claimed affairs with Trump, according to reports.

The American president vowed Monday to take action within two days following a suspected chemical attack in Syria’s Douma, saying the public would “probably” be made aware of any retaliation “after the fact.”

‘Pay a price’

Trump said anyone responsible for the attack, including Russia, will “pay a price,” and has cancelled a planned trip to Latin America to oversee the U.S. response.

“If it’s the Russians, if it’s Syria, if it’s Iran, if it’s all of them together, we’ll figure it out,” he said.

The White Helmets, a civil defense agency, blamed the Assad regime for the attack outside of Damascus, which it said killed 78 civilians and injured hundreds of others.

Russia on Tuesday vetoed a UN Security Council draft text that would have established a new expert body to determine culpability for a suspected chemical attack in Syria.

The U.S. draft resolution had the overwhelming support of the council with 12 members of the 15-member council voting in favor, and only two – Russia and Bolivia – voting against. China abstained.

Tuesday’s veto is Russia’s twelfth of council resolutions seeking to hold the Assad regime accountable for rights violations. Six of those resolutions would have condemned the regime for chemical weapons attacks.

Trump has been engaged in a flurry of diplomatic activity, calling his French and British counterparts to discuss the response to the alleged chemical attack, and discussing the matter in person with Qatari Emir Tamim bin Hamad al-Thani at the White House on Tuesday.

Trump and al-Thani “discussed Iranian and Russian malign influence, including the role Iran and Russia play to enable the Assad regime’s atrocities; the threat Iran and Russia pose to regional stability; and ways to increase cooperation between the United States and Qatar on these issues,” the White House said.

Meanwhile, Russia’s ambassador to Lebanon Alexander Zasypkin has said that his country would respond to any US missiles fired at neighbouring Syria by shooting them down and targeting their launch sites.

In an interview with Hezbollah-owned al-Manar TV on Tuesday, Zasypkin said that “if there is a US missile attack, we – in line with both Putin and Russia’s chief of staff’s remarks – will shoot down US rockets and even the sources that launched the missiles.”

The Russian envoy was referring to comments made by the Russian chief of staff, General Valery Gerasimov, who in March warned that Moscow would shoot down missiles fired towards Syria and would target their launch sites if the attacks threatened members of the Russian army.

Gerasimov said his country would use its weapons against the US if it decided to attack Syrian bases in response to a chemical attack, and if US action endangered Russian army personnel in the country.

In his interview with al-Manar, Zasypkin also said his country made some progress in Syria, including the almost-full “liberation” of Eastern Ghouta near the capital, Damascus, from armed opposition groups.

Zasypkin’s remarks come as the US and several European countries threatened to use military action against the Syrian government and its main ally, Russia, in response to a suspected chemical weapons attack on a rebel-held town.

Saturday’s attack on the town of Douma in Eastern Ghouta has killed dozens of people, mostly women and children, according to activists and local medics.

The Syrian government and Russia have denied that a chemical attack took place.

On Tuesday, rival draft resolutions by the US and Russia to set up a new expert body to probe chemical weapons attacks in Syria both failed to pass at the United Nations Security Council.

James Mattis, US defence secretary, did not rule out any military action against the forces of Syrian President Bashar al-Assad, while US ambassador to the UN, Nikki Haley, warned Washington was ready to “respond” to the attack regardless of whether the Security Council acted or not.

Meanwhile, the Syrian government has put its forces on “high alert” amid the looming threat of a US military response.

With Russian military assistance, Syrian President Bashar al-Assad launched a bloody offensive on Eastern Ghouta, which had been under rebel control since mid-2013.

Since the start of the aerial bombardment campaign on February 18, the offensive has claimed more than 1,600 civilian lives, and has, through a series of deals reached with rebel groups, internally displaced more than 45,000 people according to the United Nations.

•Based on reports by Anadolu Agency and Al Jazeera.