U.S. Ambassador Samantha Power speaks at the United Nations, Sept. 5, 2013. / CBS/PAMELA FALK
UNITED NATIONS (CBSNews.com) - U.S. United Nations Ambassador Samantha Power, a long-time passionate advocate for humanitarian intervention, is playing a spirited role at U.N. Headquarters in a bid to convince Security Council members about the need for a U.S. strike.
On Thursday, as President Obama arrived at the G-20 meeting in St. Petersburg, she held a briefing at the U.S. Mission with U.N. Security Council member nations, along with some other interested states, to give them an unclassified briefing on the U.S. intelligence regarding the responsibility of the government of Bashar al Assad in the chemical weapons attack in a Damascus suburb on August 21.
"We in the U.S. agree that at times like this, the Security Council should live up to its obligations and act," she said.
Russia's President Vladimir Putin raised expectations this week when he said that he would not exclude the possibility of Security Council action - if the United States showed definitiveproof that the Assad government was responsible.
At the G-20 on Thursday, U.N. Secretary-General Ban Ki-moon, who has pleaded with the international community to wait until the U.N. weapons inspector's report is complete and to find a consensus, met briefly with Mr. Obama.
The Secretary General from St. Petersburg called for a political solution and, through his spokesperson said that the Joint Special Representative for Syria, Lakhdar Brahimi, is on his way to Russia to help him press world leaders for an international conference on Syria.
The Secretary General implored world leaders to avoid a military response.
"While the world is focused on concerns about the possible use of chemical weapons in Syria we must push even harder for the International Conference on Syria to take place in Geneva," Ban said. "A political solution is the only way to end the bloodshed in Syria."
But, as the G-20 opened, the rhetoric between the U.S. and Russia turned sour, with the Russian president calling Secretary of State John Kerry a liar.
Back at the U.N., after days of intense negotiations, President Obama's U.N. Ambassador was no holds barred when asked by CBS News about Putin's comment that Russia just needs proof.
"Russia continues to hold the Council hostage and shirk its international responsibility, including as party to a chemical weapons convention," Power said.
She was equally scornful of the U.N. Security Council, listing all the efforts at the Council in which condemnation and use of force was proposed by the U.S. and the U.K.
"Instead," Power said, "the system has protected the prerogatives of Russia, the patron of a regime that would brazenly stage the world's largest chemical weapons attack in a quarter century, while U.N. inspectors were across town."
Will the U.N. be relevant and able to support a Council Resolution or sponsor an international settlement between the Syrian rebels and the opposition? Not likely, say U.N. diplomats, if even the U.S. and Russian President can't even agree to meet while the Middle East is falling apart.
Calling on U.N. member states to agree with the U.S. assessment, Obama's U.N. Ambassador was clear: "It's in our interests and that of all member states to respond decisively to this horrific attack."
© 2013 CBS Interactive Inc. All Rights Reserved.