"Only after pursuing a wide range of non-military measures to prevent and halt chemical weapons use did President Obama conclude that a limited military strike is the right way to deter Assad from continuing to employ chemical weapons like any conventional weapon of war," Rice said.
She argued the Assad regime's attack is not only a direct affront to that norm but also a threat to global security, including the security of the United States.
"Failing to respond makes our allies and partners in the region tempting targets of Assad's future attacks...And increases the risk of violence and instability as citizens across the Middle East and North Africa continue to struggle for their universal rights," she said.
Rice said: "We cannot allow terrorists bent on destruction or a nuclear North Korea or an aspiring nuclear Iran to believe for one minute that we are shying away from our determination to back up our long- standing warnings."
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"Any President, Republican or Democrat, must have recourse to all elements of American power to design and implement our national security policy, whether diplomatic, economic or military," she added.
With all the attention given to the prospect of limited military strikes, Rice underscored that such action is, by no means, the sum total of US policy towards Syria.
"On the contrary, any such strikes would complement and reinforce our broader Syria strategy, which we continue to pursue with allies and partners," she said.
The US, she said, will continue to increase pressure on the Assad regime to come to the table and negotiate.
"Notably, during our discussions in St Petersburg, we sensed more urgency among key players to bring the parties to the negotiating table to jump start a political transition.
"The United States shares that sense of urgency, and our intention is to renew our push for the UN-sponsored Geneva process following any limited strikes," she said.