Obama: Use of chemical weapons in Syria would be 'game-changer'

President Obama said Wednesday that the use of chemical weapons in Syria would be a "game-changer" that would demand action from the international community, though he stressed that the U.S. and other nations are still trying to determine whether those weapons were used.

The president addressed the issue during a joint press conference with Israeli Prime Minister Benjamin Netanyahu, on his first visit to Israel as commander-in-chief. Syria, as well as Iran, were at the top of the agenda in a meeting between the two leaders earlier in the day.

Asked about allegations that chemical weapons have been used in Syria, Obama stressed that "we have to make sure that we know exactly what happened."

Once the facts are established, Obama said, "I have made clear that the use of chemical weapons is a game-changer."

He said the use of those weapons would create an even more "horrific scene" in Syria -- and the "international community has to act on that additional information."

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Any confirmation that the Assad regime used the weapons would put pressure on the Obama administration to follow through on warnings that such an act would constitute crossing a "red line." Syrian rebels and Assad's regime on Tuesday accused each other of using those weapons, though Obama said he is "deeply skeptical of any claim" that the opposition was behind that kind of attack.

Officials from the U.S. and Israel, though, were sending conflicting signals Wednesday about the potential evidence supporting such an attack.

Shortly before Obama spoke, U.S. Ambassador to Syria Robert Ford said during testimony on Capitol Hill that “so far we have no evidence to substantiate those reports."

“I want to underline that we are looking very carefully," Ford said.

His comments before the House Foreign Affairs Committee were made within hours of Yuval Steinitz, Israel’s new minister of intelligence and strategic affairs, saying in an interview the weapons were used. However, he would not say how he reached the conclusion or which side used them.

"It is apparently clear that chemical weapons were used," he said. "The fact they apparently used chemical weapons against civilians needs to worry us and shows the urgency of taking care of the issue."

Steinitz said that after Iran's nuclear program, the fate of Syria's chemical weapons is the second most urgent issue that will be discussed with Obama during his 48-hour visit.

There have been many reports and rumors of such weapons being used throughout the war but no attack has yet been confirmed. Israel has repeatedly expressed concern that Syria's chemical arsenal could fall into the hands of anti-Israel militants like Lebanon's Hezbollah, an Assad ally, or an Al Qaeda-linked group fighting with the rebels.

More than 70,000 civilians have been killed in the attempt to overthrow Assad, and an estimated 1 billion others have fled to neighboring countries, including roughly 450,000 to Jordan.

Ford also testified that the U.S. continues to provide hundreds of millions of dollars in humanitarian aid. However, the administration maintains a policy of trying to negotiate a peace settlement and not providing weapons to opposition forces.

He also declined to answer questions about what would be the consequence should U.S. officials find Syria crossed a “red line” by using chemical weapons.

Obama has declared the use, deployment or transfer of the weapons would be a red line for possible U.S. military intervention.

“I am certain they have been discussed but I don't want to speculate,” Ford said. “I don't want to go there."

The Syrian state-run SANA news agency said Tuesday "a missile containing a chemical substance" was fired at the village by "terrorists" -- the term it uses for rebels. Syria's Deputy Foreign Minister Faysal Mekdad said 31 people were killed.

SANA added that more than 100 others were wounded, some of them critically, and it published pictures showing casualties, including children, on stretchers in what appears to be a hospital ward. None showed signs of physical injuries. The rebels quickly denied using chemical weapons and accused government forces of doing so.

The Associated Press contributed to this report.