Facing her first serious Syria showdown at the Security Council, the ambassador, Nikki R. Haley, also used her remarks at an emergency session to blame Russia for blocking a robust response to the attack on Tuesday on a northern Syrian town, which has incited widespread condemnation. The death toll was reported to exceed 100.
The United States, France and Britain have accused the Syrian government of responsibility and bitterly criticized Russia — Syria’s main ally in the six-year-old war — for objecting to a resolution they drafted condemning the attack.
Russia has said that insurgents may have been responsible, or that the attack may have been fabricated to embarrass President Bashar al-Assad of Syria.
“Time and time again, Russia uses the same false narrative to deflect attention from their allies in Damascus,” Ms. Haley said. “How many more children have to die before Russia cares?”
She closed her remarks with an ominous warning. “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.
She did not provide further details. But the hint of acting alone was striking, suggesting that she was willing to articulate a position even before her boss.
Shortly after her remarks, President Trump expressed his own tougher tone toward Mr. Assad. At a White House news conference on Wednesday, Mr. Trump said that the attack had “crossed a lot of lines for me” and that his attitude toward “Syria and Assad has changed very much.”
The French ambassador to the United Nations, François Delattre, called on Russia to stand up to the use of chemical weapons and on the United States to show leadership on Syria. Asked about his American counterpart’s suggestion of unilateral action in the absence of a consensus, Mr. Delattre demurred. “Action by the Security Council would be by far the best option,” he said. “I’m concerned by inaction at this stage, the risk of inaction.”
The draft resolution “expresses its determination that those responsible must be held accountable” but provided no concrete measure to do so. It reminded the Syrian government that it was obliged to cooperate with international investigators looking into the use of chemical weapons, including by turning over all flight logs, flight plans and the names of commanders in charge of air operations on the day of the strike. It also asked the secretary general, António Guterres, to provide monthly reports on whether the Syrian government was cooperating.
The British envoy, Matthew Rycroft, pushed his fellow diplomats to act or lose all credibility in the eyes of the public. “They view us as a table of diplomats doing nothing, our hands tied behind our backs, beholden to Russian intransigence,” he said.
Russia dismissed the comments, saying, “At this stage, we don’t see a particular need.” Its deputy ambassador, Vladimir Safronkov, went on to scold its drafters for expressing “horror” at the attack: “Have you even checked what you wrote? This draft was prepared in a hasty way.”
After the Council meeting ended, diplomats said that they were continuing to negotiate and that no vote had been scheduled.
In Brussels, at a meeting of donor countries for Syrian humanitarian relief convened by the European Union, Mr. Guterres declared that “war crimes are going on in Syria.”
Asked whether Mr. Assad’s government was responsible, Mr. Guterres called for “a very clear investigation to remove all doubts.”
Condemnation also came from Pope Francis, who called the attack “an unacceptable massacre”; the NATO secretary general, Jens Stoltenberg, who deplored “the use of these barbaric weapons”; and Donald Tusk, president of the European Council, who said that Syria’s government bore primary responsibility.
The Brussels conference produced pledges of $6 billion for 2017, Christos Stylianides, the European commissioner for humanitarian aid, announced Wednesday evening when the meeting concluded.
The war in Syria has taken nearly 400,000 lives, monitoring groups have said, and it has displaced roughly half of all Syrians from their homes.
Author: SOMINI SENGUPTA and RICK GLADSTONE