At a press conference held Monday to address the United States' position on allegations that Syrian President Bashar al-Assad used chemical weapons on residents of a Damascus suburb, Secretary of State John Kerry said the world must stand up to ensure accountability for the "indiscriminate use of chemical weapons," adding that such violations of international law "cannot be violated without consequences."
"The firsthand accounts from those on the ground all strongly indicated everything the images are already screaming at us is real -- that chemical weapons were used in Syria," Kerry said.
Kerry's statements in which he termed a "moral obscenity" that "should shock the conscience of the world" came as the U.S. and the international community mull intervention in Syria to prevent further chemical attacks.
Kerry also said that President Barack Obama would make an "informed decision" on how to respond to the chemical attack. Meanwhile, House Speaker John Boehner's spokesman said the Ohio lawmaker told the White House that he must consult Congress and have clearly defined objectives before taking any action in Syria.
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Earlier in the day, U.N. chemical weapons investigators reached their destination on the outskirts of Damascus, hours after unknown snipers fired on them as they attempted to enter the site of Wednesday's alleged gas attack.
A spokesperson for U.N. Secretary-General Ban Ki-moon said the investigation team was hit by a barrage of bullets from rooftops. No injuries were reported, though one vehicle was rendered inoperable.
Kerry said that the gunfire "only weakens the regime's credibility."
In agreeing to allow the chemical inspection team into Syria, the United Nations said Damascus had agreed to a cease-fire while the investigators inspect the site.
Syrian state media blamed the barrage of sniper bullets targeting the U.N. team on "terrorist gangs."
But Wassim al-Ahmad, a council member of the city of Moadamiya, where one of the alleged gas attacks took place, said members of a pro-government militia called the Popular Committees were responsible for firing at the U.N. team.
Meanwhile, a Syrian doctor in Moadamiya told Reuters that U.N. investigators had reached victims of the alleged gas attack.
"We are in the Rawda Mosque, and they are meeting with the wounded. Our medics and the inspectors are talking to the patients and taking samples from the victims now," he said.
An opposition activist said a large crowd of people eager to air their grievances to the U.N. team was growing. There was also a plan for the experts to take samples from corpses.
Syria agreed Sunday to allow the U.N. experts to inspect the site of the alleged attack. But the United States and other countries said evidence had probably been destroyed by heavy government shelling of the area over the past five days. It said the offer to allow inspectors came too late.
International speculation has mounted in recent days over the possibility of global powers' launching a military intervention in Syria to prevent more chemical attacks.
Syrian Deputy Foreign Minister Faysal Mikdad told The Associated Press in an interview in Damascus that such an attack would trigger "chaos in the entire world."
"If individual countries want to pursue aggressive and adventurous policies, the natural answer...would be that Syria, which has been fighting against terrorism for almost three years, will also defend itself against any international attack," he added.
Assad, who has been fighting a popular revolt for more than two years, said accusations that his forces used chemical weapons were politically motivated and warned the United States against intervening.
"Would any state use chemicals or any other weapons of mass destruction in a place where its own forces are concentrated? That would go against elementary logic. So accusations of this kind are entirely political," he said in an interview with Russian newspaper Izvestia.
"Failure awaits the United States, as in all previous wars it has unleashed, starting with Vietnam and up to the present day," he added.
The United States was not alone in upping the rhetorical ante against Assad Monday.
French Foreign Minister Laurent Fabius said no decision had been made on a military intervention but that any response would be "proportionate."
"It will be negotiated in coming days," Fabius told Europe 1 radio on Monday. He said that the lack of a U.N. blessing was problematic but that all options remained on the table.
"The only option that I can't imagine would be to do nothing," Fabius said.
The German government suggested for the first time on Monday that it would support an international military response if it is confirmed that Assad's troops attacked Syrians with chemical weapons.
Steffen Seibert, spokesman for Chancellor Angela Merkel, said that if U.N. inspectors confirmed that Syria used chemical weapons, "it must be punished."
Russian Foreign Minister Sergei Lavrov said Monday that any military action without U.N. approval would be a "grave violation of international law." Russia is Syria's most stalwart ally on the U.N. Security Council and would likely veto any resolution aimed at authorizing outside military force.
Al Jazeera and wire services