President Obama has lost a golden opportunity at the G20 Summit in St. Petersburg to step back from undertaking a military assault on Syria, that promises to create hell for Syria's civilian population and to unleash consequences that can extend far beyond Syria's borders.

At his press conference held after the summit, President Obama warned:

"Syria's escalating use of chemical weapons threatens its neighbors, Turkey, Jordan, Lebanon, Iraq, Israel. It threatens to further destabilize the Middle East. It increases the risk that these weapons will fall into the hands of terrorist groups. But more broadly, it threatens to unravel the international norm against chemical weapons embraced by 189 nations, and those nations represent 98 percent of the world's people."

President Obama revealed there had been the following unanimity among all G20 members:

"It was unanimous that chemical weapons were used, a unanimous conclusion that chemical weapons were used in Syria. There was a unanimous view that the norm against using chemical weapons has to be maintained. That these weapons were banned for a reason and that the international community has to take those norms seriously."

Given such unanimity -- why were the G20 participants not able to agree on an international response to ending the use of chemical weapons in Syria with the authority of a United Nations Security Council Resolution to provide the international legitimacy for any such proposed action?

Their failure to do so was apparently due to President Obama and President Putin of Russia continuing to lock horns on their different views as to who was responsible for using chemical weapons in Syria -- rather than seeking constructive ways to get chemical weapons out of Syria to prevent their future use in the ongoing 30-month conflict that has so far defied international attempts at resolution.

President Obama made this diplomatic deadlock very clear when referring to his "candid and constructive conversation" with President Putin held on the sidelines of the plenary session:

"And on Syria, I said, listen, I don't expect us to agree on this issue of chemical weapons use. Although it is possible that after the U.N. inspectors' report, it may be more difficult for Mr. Putin to maintain his current position about the evidence." [That the chemical weapons were used by the rebels -- not by the Assad regime.]

President Obama sought to assure the world that his military response would be limited:

"And our response, based on my discussions with our military, is that we can have a response that is limited, that is proportional, that when I say limited, it's both in time and in scope, but that is meaningful and that degrades Assad's capacity to deliver chemical weapons, not just this time, but also in the future, and serves as a strong deterrent."

With respect -- no one could possibly predict the attainment of these objectives with any degree of confidence or accuracy -- as the president himself confessed:

"Now, is it possible that Assad doubles down in the face of our action and uses chemical weapons more widely? I suppose anything's possible, but it wouldn't be wise. I think, at that point, mobilizing the international community would be easier, not harder. I think it would be pretty hard for the U.N. Security Council at that point to continue to resist the requirement for action, and we would gladly join with an international coalition to make sure that it stops."

Only concerted international action under United Nations Mandate to enforce the removal of such chemical weapons from Syria can guarantee against their future use by either the Assad regime or the rebel forces.

Such an option was put to President Obama at his press conference:

"I wonder if you leave here and return to Washington, seeing the skepticism there, hearing it here, with any different ideas that might delay military action. For example, some in Congress have suggested giving the Syrian regime 45 days to sign the Chemical Weapons Convention, get rid of its chemical stockpiles, do something that would enhance the international sense of accountability for Syria, but delay military action.

Are you, Mr. President, looking at any of these ideas? Or are we on a fast track to military action as soon as Congress renders its judgment one way or the other?"

It was at this point that the opening available to President Obama to possibly step back from his planned military action -- and instead initiate international action at the UN to collect and destroy these chemical weapons -- was not grabbed with open arms.

His response was dismissive:

"So far at least, I have not seen ideas presented that, as a practical matter, I think would do the job"

Hopefully Congress will push President Obama to pursue its option, especially as the president stated:

"My goal is to maintain the international norm on banning chemical weapons. I want that enforcement to be real. I want it to be serious. I want people to understand that gassing innocent people, you know, delivering chemical weapons against children, is not something we do.

...I'm listening to Congress. I'm not just doing the talking. And if there are good ideas that are worth pursuing, then I'm going to be open to them."

Collecting and destroying chemical weapons in Syria still remains the most noble humanitarian objective worth pursuing.

Creating possible hell on earth by another American military adventure without UN authorization will be disastrous.