UNITED NATIONS - The United States may take unilateral action in Syria if the United Nations fails to respond to a suspected chemical attack in Syria which is reported to have killed dozens of civilians, including children, American Ambassador to UN Nikki Haley has warned.

The warning came as the UN Security council held an emergency meeting on Wednesday about the atrocity, after Washington, Paris and London drew up a draft statement condemning the attack and demanding an investigation. “When the United Nations consistently fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action,” Ambassador Haley told the 15-member Council.

Meanwhile, Russia threatened to veto any resolution by the UN Security Council on a claiming it is based on “false information.” Russia denied on Wednesday that Syrian President Bashar al-Assad was to blame for a poison gas attack and said it would continue to back him, opening a rift between the Kremlin and Donald Trump’s White House, which initially sought warmer ties.

Francois Delattre, France’s permanent representative to the UN, described the attack as a “chemical horror.” “We hope this draft resolution can unite the international community in refusing what is unacceptable,” he said at the Security Council meeting.

Matthew Rycroft, the UK’s permanent representative, said the UN was “seeing the consequences” of previous vetoes by Russia and China which only served to encourage Assad to keep carrying out attacks on his own people. “They [the consequences] are printed on the faces of the children of a regime that will stop at nothing to hold on to power,” he said.

“Russia will say they don’t have any information...and yet we are seeing all the signs of a nerve agent capable of killing hundreds of people. “This does not look like the opposition, or terrorists, it bears all the hallmarks of the Assad regime, and the use of chemical weapons is a war crime,” he added. He said that Assad was humiliating Russia in the eyes of the world by showing how empty Syria’s promise was to remove chemical weapons, and called on Russia to join him in condemning the attack.

The Russian deputy envoy to the UN, Vladimir Safronkov, criticized the draft resolution for being unbalanced and jumping to conclusions. It said the document would have to include several amendments, such as calling on the rebels controlling the area to provide full access to UN investigators and setting an unbiased and comprehensive probe into the incident as the primary goal of the resolution.

Meanwhile, US President Donald Trump warned Wednesday that Bashar al-Assad’s Syrian regime had crossed a line with its latest alleged chemical attack and faces a US response.

Previously the White House has said its sole focus in Syria is defeating the militant Islamic State group, not on ending Assad’s civil war against opposition fighters. But Trump and other senior US officials said that the latest attack, which doctors say caused the agonizing deaths of at least 72 people, had changed the calculus.

And he renewed his criticism of his predecessor Barack Obama who in 2013 famously failed to take action after Assad crossed a “red line” with a previous chemical attack. “It crossed a lot of lines for me,” Trump said, at a joint White House news conference with Jordan’s King Abdullah.

“When you kill innocent children, innocent babies, little babies ... that crosses many, many lines, beyond a red line, many, many lines,” he warned.

“I will tell you, it’s already happened, that my attitude towards Syria and Assad has changed very much ... You’re now talking about a whole different level.”

Trump did not go into detail about what a US response to the atrocity will be - and he has previously opposed deeper US military involvement in Syria’s civil war.

But his statement that his attitude had changed came after the US ambassador to the United Nations, Nikki Haley, had warned of unilateral American action.

“When the United Nations consistently fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action,” she said.