The ambassador invoked Article 51 of the UN charter that recognizes the right to self-defence by any state if it comes under attack.
The United States is consulting with Britain and France about a joint military response to an alleged toxic gas attack in the rebel-held town of Douma that medics and rescuers said killed at least 40 people on Saturday.
US Ambassador Nikki Haley told the council that no decision had been taken about military action, but that any use of force would be in response to multiple chemical attacks carried out by President Bashar al-Assad's forces.
Citing US estimates that Assad has used chemical weapons "at least 50 times" in the seven-year war, Haley said: "All nations and all people will be harmed if we allow Assad to normalize the use of chemical weapons."
Syria and Russia have denied using poisonous gas in Douma on April 7, with Russian Foreign Minister Sergei Lavrov saying that Moscow had "irrefutable" evidence that the attack in Douma was a "staged event."
Russia has told the United States that it will not allow its troops on the ground in Syria to be put at risk by military action, even though the two countries have contacts to avoid such direct confrontation.
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