JERUSALEM, Israel -- The international community is calling for clarity in the case of fresh allegations that the Syrian regime is using chemical weapons against rebels and civilians.
"This represents, no matter what the conclusions are, a serious escalation, with grave humanitarian consequences and human consequences," United Nations Deputy Secretary-General Jan Eliasson said.
U.N. investigators are in Syria waiting to examine the situation on the ground.
Syrian regime forces fired intense artillery and rocket barrages Wednesday into eastern suburbs of Damascus in what some claim was a "poisonous gas" attack that killed hundreds of people, including many children.
"Human Rights Watch has spoken today to 10 residents from eastern Ghouta, including two physicians," said Lama Fakih, a Human Rights Watch researcher on Syria and Lebanon.
"The residents consistently told us about field hospitals in the area being overwhelmed with civilians who were suffering from a range of symptoms, including nausea, suffocation, foaming at mouth, and dilated pupils," Fakih said.
Amateur video with shocking images appeared to show the effects of a gas attack on civilians. The Syrian government called claims of a chemical attack "absolutely baseless."
Last March, President Obama suggested the use of chemical weapons might force the U.S. to intervene in the Syrian civil war.
"To use potential weapons of mass destruction on civilian populations crosses another line, and that is going to be a game-changer," Obama said then.
A reporter later pressed the White House about the comment.
"Jay, did the president mean it when he said use of chemical weapons are a game changer in Syria?" reporter Jonathan Karl asked White House Press Secretary Jay Carney.
"Yes, he did," Carney answered.
"So what does that mean?" Karl asked.
"The president made clear that the use of or the transfer to terrorist groups of chemical weapons by the Assad regime would be a crossing a red line, and he retains all options to respond to that," Carney responded.
"Including military force? Including military?" Karl pressed, to which Carney replied, "All options, all options."
Middle East expert Walid Phares said any U.S. or Western intervention in Syria's more than 2-year-old civil war would be complicated.
"The reality is that Syria is not any more a national battlefield as was the case in the Libya civil war because the regime there is supported by the Iranian regime, by the Iraqi government in some sort of fashion, and also by Hezbollah, which is fighting inside Syria," Phares told CBN News Wednesday.
"There's a whole alliance and of course the opposition is backed by Turkey, by Qatar, by other Arab countries," he continued. "The most concerning thing about the opposition is it's infiltration by al Qaeda."
Phares said any U.S. action would have to consider the regional elements. For now, he said, the international community could try to set up security zones in the north and south for refugees and Syrian civilians fleeing the fighting.