President Obama has said that he wants to give diplomacy a chance to avoid military strikes on Syria for its alleged use of chemical weapons, but made a forceful case for why the US must act if negotiations fail.
Calling the US "the anchor of global security," Obama in a televised address offered moral, political and strategic arguments for being ready to launch limited military strikes while trying to negotiate a diplomatic solution.
Obama termed the Russian proposal an "encouraging" sign to place Syria's chemical weapons under international control.
Obama said that he has asked his military to continue maintaining its aggressive posture in the region pending a diplomatic solution to the Syrian crisis.
"I've ordered our military to maintain their current posture, to keep the pressure on Assad and to be in a position to respond if diplomacy fails," he said.
He, however, said it is too early to tell if the Russian effort would succeed.
"It's too early to tell whether this offer will succeed, and any agreement must verify that the Assad regime keeps its commitments. But this initiative has the potential to remove the threat of chemical weapons without the use of force, particularly because Russia is one of Assad's strongest allies," he said.
"I have therefore asked the leaders of Congress to postpone a vote to authorise the use of force while we pursue this diplomatic path. I'm sending Secretary of State John Kerry to meet his Russian counterpart on Thursday, and I will continue my own discussions with (the Russian) President (Vladimir) Putin," Obama said in his address to the nation.
"I've spoken to the leaders of two of our closet allies, France and the United Kingdom. And we will work together in consultation with Russia and China to put forward a resolution at the UN Security Council requiring Assad to give up his chemical weapons and to ultimately destroy them under international control," he said in his address from the White House.
The 15-minute nationally televised speech initially was planned as Obama's final push to win support from a sceptical public and Congress for his planned attack on Syria for what his administration calls a major chemical weapons attack on August 21 that killed more than 1,400 people in suburban Damascus.
"We'll also give UN inspectors the opportunity to report their findings about what happened on August 21. And we will continue to rally support from allies, from Europe to the Americas, from Asia to the Middle East who agree on the need for action," Obama said.
"The Russian government has indicated a willingness to join with the international community in pushing Assad to give up his chemical weapons. The Assad regime has now admitted that it has these weapons and even said they'd join the chemical weapons convention, which prohibits their use," he said.
Hours ahead of his address to the nation, Obama drove down to the Capitol Hill to brief lawmakers on his assessment of the Syrian situation, and received inputs on his decision
to go for a limited military strike against Assad regime.
In his address, Obama reiterated that it is in the national security interest of the US to go for a limited targeted military strike against the Assad regime holding it accountable for using chemical weapons against its own people.
"A failure to stand against the use of chemical weapons would weaken prohibitions against other weapons of mass destruction and embolden Assad's ally, Iran, which must decide whether to ignore international law by building a nuclear weapon or to take a more peaceful path," he said.
"This is not a world we should accept. This is what's at stake. And that is why, after careful deliberation, I determined that it is in the national security interests of the United States to respond to the Assad regime's use of chemical weapons through a targeted military strike," Obama said.
The purpose of this strike would be to deter Assad from using chemical weapons, to degrade his regime's ability to use them and to make clear to the world that the US will not tolerate their use.
"That's my judgement as commander in chief," he said.
Obama cautioned against giving the impression that the US military strike would be just a pin prick.
"I will not put American boots on the ground in Syria. I will not pursue an open-ended action like Iraq or Afghanistan. I will not pursue a prolonged air campaign like Libya or Kosovo. This would be a targeted strike to achieve a clear objective: deterring the use of chemical weapons and degrading Assad's capabilities," he said.
"Others have asked whether it's worth acting if we don't take out Assad. As some members of Congress have said, there's no point in simply doing a pinprick strike in Syria. Let me make something clear: The United States military doesn't do pinpricks," he said.
Making his case for military strike if the diplomatic option fails, Obama said when dictators commit atrocities, they depend upon the world to look the other day until those horrifying pictures fade from memory.
"But these things happened. The facts cannot be denied. The question now is what the United States of America and the international community is prepared to do about it, because what happened to those people, to those children, is not only a violation of international law, it's also a danger to our security," he said.
"If we fail to act, the Assad regime will see no reason to stop using chemical weapons. As the ban against these weapons erodes, other tyrants will have no reason to think twice about acquiring poison gas and using them.
"Over time our troops would again face the prospect of chemical warfare on the battlefield, and it could be easier for terrorist organizations to obtain these weapons and to use them to attack civilians," he said.
"If fighting spills beyond Syria's borders, these weapons could threaten allies like Turkey, Jordan and Israel.
"And a failure to stand against the use of chemical weapons would weaken prohibitions against other weapons of mass destruction and embolden Assad's ally, Iran, which must decide whether to ignore international law by building a nuclear weapon or to take a more peaceful path," Obama said.
"This is not a world we should accept," said the US President.