By Susan Cornwell
WASHINGTON (Reuters) - U.S. national security adviser Susan Rice returned to center stage on Monday to deliver a forceful call for limited U.S. military strikes in Syria, nearly a year after her comments about another foreign crisis turned her into a target for Republican anger.
In her first major speech since the former U.S. ambassador to the United Nations started her White House job in July, Rice said Washington had to respond to the "atrocity" and "outrage" of chemical weapons use in Syria.
President Barack Obama's administration intended to return to a diplomatic track to try to resolve the Syria conflict, but this would be following "any limited (military) strikes" to degrade that country's chemical weapons capabilities, Rice said.
"This most recent atrocity is particularly gut-wrenching," she said in a speech at the New America Foundation in Washington, as part of Obama's push to persuade Congress and a doubtful public to support military strikes against Syria.
She described the "hellish chaos and terror" of the August 21 chemical weapons attack, with "those little children, laying on the ground, their eyes glassy, their bodies twitching." The Obama administration says more than 1,400 people were killed, including 400 of them children.
"This cannot stand," Rice said. "As the one indispensable leader in the world, the United States of America can and must take action - carefully, responsibly, purposefully - to reduce the chances of such an outrage happening again."
It was the kind of blunt language Rice was known for before criticism of comments she made about a militant attack on a U.S. diplomatic compound in Benghazi, Libya last year forced her off the public stage to take more of a behind-the scenes foreign policy role.
Last September, while still serving as U.S. ambassador to the United Nations, Rice said the attack that killed four Americans at the U.S. mission in Benghazi, was the work of a spontaneous crowd, instead of Islamic militants.
When this proved false, Republican lawmakers charged Rice had been trying to protect Obama during his re-election campaign, which the White House disputed.
Rice eventually withdrew her name from consideration to be nominated as Obama's second-term secretary of state and former Senator John Kerry got the job. Instead, Rice was appointed national security adviser, which does not require Senate confirmation.
She has been relatively quiet since beginning her new duties at the White House. Syria is her most serious challenge so far and she has occasionally tweeted her views on the importance of holding President Bashar al-Assad accountable for the chemical weapons attack.
On Monday, Rice asserted there was no doubt who was responsible for the chemical weapons attack and said Assad had used chemical weapons on a small scale several times before.
"The intelligence we've gathered reveals senior (Syrian) officials planning the attack and then afterwards, plotting to cover up the evidence by destroying the area with shelling," she said. Assad has denied he was behind it and said in an interview with CBS that evidence was not conclusive there had been such an attack.
Rice did not say what she thought of Russia's proposal that Syria's chemical weapons be put under international control, or a suggestion by U.N. Secretary General Ban Ki-moon that the Security Council could demand Damascus move its chemical arms stocks to a place where they could be safely destroyed.
However, she declared that past U.N. behavior on Syria had been "shameful," especially the actions of Russia and China, which opposed Security Council resolutions condemning the Syrian government. She also threw cold water on the idea that the council would now uphold an international ban against the use of chemical weapons with sanctions or an authorization of force.
"Let's be realistic. It's just not going to happen now," Rice said. "Believe me. I know. I was there for all of those U.N. debates and negotiations on Syria. I lived it. It was shameful."
(Additional reporting by Deborah Charles and Steve Holland.; Editing by Alistair Bell and Christopher Wilson)