(WASHINGTON) -- Secretary of State John Kerry on Friday made an impassioned case for punishing Syria, stating that a chemical attack by the regime of President Bashar al-Assad killed 1,429 people, a toll that he said included 426 children. "Instead of being tucked safely in their beds," there were "rows and rows" of dead children, Kerry said.
The secretary of state spoke shortly before President Obama was scheduled to address the country.
Kerry said it was important to hold the Assad regime responsible for the alleged use of chemical weapons as a warning to other countries and groups.
He said the Obama administration was releasing Friday its unclassified report on the chemical attack to the U.S. public so "you can read for yourselves" the evidence amassed.
The secretary said the review was "done more than mindful of the Iraq experience" in which claims that Iran had weapons of mass destruction were later determined to be unfounded. "We will not repeat that experience," Kerry said.
In reviewing the evidence, Kerry said, "We know that the Assad regime has the largest chemical weapons program in the entire Middle East. We know they have used those weapons numerous times."
He said the evidence shows that Syrian chemical weapons teams were in the area of the Damascus suburb in advance of the attack and were told to put on gas masks. He said the United States knows where the rockets "were launched from and where and when they landed."
"And we know that 90 minutes later all hell broke loose” on social media, he said.
The reports from Syrian civilians described "victims with breathing difficulty, people twitching and coughing, foaming at the mouth ... and death."
He said doctors and nurses who treated the victims reported no gunshot wounds. The dead, he said, were "unstained by a single drop of blood."
He put the death toll at 1,429.
Kerry spoke as U.N. weapons inspectors headed out for one final day of investigations after a delayed start Friday morning, with the United States signaling it was ready to launch a military campaign against the Syrian regime on its own.
The U.N. team was seen leaving their Damascus hotel Friday morning, only to turn back moments later. Journalists in Syria's capital reported heavy government shelling in nearby rebel-controlled suburbs but the U.N. team got underway around noon local time.
Traveling with the U.N. convoy Friday morning, the BBC reporter in Damascus tweeted that the inspectors unexpectedly visited a military hospital instead of the sites of the reported Aug. 21 chemical weapons attack. The U.N. team plans to leave the country Saturday morning, one day ahead of schedule, and will report immediately to U.N. Secretary-General Ban ki-Moon.
While the international community awaits the results from the U.N. investigation, Washington is regrouping after losing British support Thursday night. Dealing a major blow to its stalwart ally, the British House of Commons voted down a motion authorizing military action in Syria.
Britain "will not be involved" in any military strikes on Syria, U.K. Defense Secretary Philip Hammond said.
He added, "I don't expect that the lack of British participation will stop any action."
National Security spokeswoman Caitlin Hayden suggested Thursday that the United States was prepared to move ahead with or without U.K. support.
"As we've said, President Obama's decision-making will be guided by what is in the best interests of the United States," Hayden said.
"He believes that there are core interests at stake for the United States and that countries who violate international norms regarding chemical weapons need to be held accountable."
Such comments stand in contrast to the tone senior officials took last week, saying repeatedly that the United States would only act in coordination with its allies.
Defense Secretary Chuck Hagel said Friday morning the United States was still on the hunt for a coalition.
"Our approach is to continue to find an international coalition that will act together," Hagel told reporters in Manila, the Philippine capital. "And I think you're seeing a number of countries state, publicly state, their position on the use of chemical weapons."
Hagel added, "Every nation has a responsibility to make their own decisions, and we respect that of any nation."
The defense secretary is expected to return to Washington later Friday.
After Hagel's comments, France hinted that it might follow the United States' lead.
French President Francois Hollande told Le Monde in an interview published Friday that he supported "firm" punitive action against the Syrian regime.
"Each country is sovereign to participate or not in an operation," Hollande told the French newspaper. "That is valid for Britain as it is for France."
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