The European Union's foreign-policy chief, Catherine Ashton, says the EU's 28 members have agreed that available information seemed to show strong evidence that the Syrian government used chemical weapons last month.
"Information from a wide variety of sources confirms the existence of such an attack," Ashton said.
"And seems to indicate strong evidence that the Syrian regime of is responsible for this attack as it is the only one that possesses chemical-weapons agents and the means of their delivery in a sufficient quantity."
Ashton said that faced with such crimes, the EU couldn't remain idle. "A clear and strong response is crucial to make clear that such crimes are unacceptable and that there can be no impunity," she said.
Ashton was speaking after EU foreign ministers met with U.S. Secretary of State John Kerry in Vilnius on September 7.
On leaving the Lithuanian capital for talks in Paris, Kerry welcomed the "strong statement...that supports the efforts to hold the Assad regime accountable for what he's done."
He is expected to hold more talks with Arab and European diplomats in Paris.
Kerry's trip comes amid skepticism about the wisdom of a U.S. attack on the Syrian regime from many U.S. lawmakers, ordinary Americans, and members of the international community.
EU Members Lukewarm On Intervention
The EU has been divided over U.S. plans for military action to punish President Bashar al-Assad's regime for the August 21 attack, which Washington says killed more than 1,400 people.
Several EU members have urged Washington to hold off on any military action until UN inspectors report on the suspected use of chemical weapons last month.
Germany has said it will not take part in any military action. The British Parliament has voted against Britain's participation in military strikes.
French President Francois Hollande, who initially backed military action, said on September 6 he would wait for the UN report before deciding whether to intervene militarily.
Ashton said the EU hoped UN inspectors will release a preliminary report as soon as possible. She also called on the UN Security Council "to unite in its efforts to prevent any further chemical attack."
President Barack Obama said on September 7 that inaction in Syria was not an option for the United States.
In his weekly radio and Internet address, Obama said the United States could not "turn a blind eye" to Syria. He also said he did not want a costly and protracted war.
"What we are not talking about is an open-ended intervention. This would not be another Iraq or Afghanistan," Obama said. "There would be no American boots on the ground. Any action we take would be limited both in time and scope."
Obama has asked Congress to authorize the use of military force in Syria.
Congress reconvenes on September 9, and Obama will be addressing the nation on September 10 about possible military strikes in Syria.
Lawmakers who have expressed doubts about a strike have cited concerns about whether the United States could be drawn into a prolonged conflict, and whether such an operation will strengthen Islamic extremists who are fighting on the opposition side.
'Costs Of Inaction'
Kerry has been among the most vocal administration officials arguing in favor of a military operation. In an article published on September 6, Kerry wrote that any U.S. operation would be aimed at deterring the government from launching another chemical-weapons attack.
Kerry added that the "costs of inaction" would be much greater than the costs of taking action, because the world community must send the message that the use of chemical arms will not be tolerated.
Ten countries, including nine Group of 20 (G20) members, joined the United States in a statement calling for a "strong international response."
The statement, issued at the G20 summit in St. Petersburg, says evidence "clearly points to the Syrian government" being responsible for the attack. However, the statement did not specifically back the use of military force.
The countries signing the document were Australia, Britain, Canada, France, Italy, Japan, South Korea, Saudi Arabia, Spain, and Turkey.
Russia, however, remains steadfastly opposed to any U.S. military action against Syria’s government, which is a major ally of Moscow in the Middle East. The G20 summit failed to result in any narrowing of the starkly opposed positions of Moscow and Washington.
President Vladimir Putin reiterated his view that any U.S. military action would be "counterproductive." Putin has said any use of force must be backed by the United Nations Security Council.
Putin added that he expected Russia to continue cooperating with the Syrian government, including providing weapons and humanitarian aid.
The Syrian government has denied carrying out the August 21 chemical attack in east Damascus, instead accusing rebel forces of being responsible.
Obama administration officials have said the United States may have to act on its own against the Syrian regime because Russia has repeatedly blocked moves for an international response in the Security Council.
With reporting by Reuters, AP and AFP