The prospect of a dramatic U.S.-led intervention into Syria's chaotic civil war stems from the Western assertion — still not endorsed by U.N. inspectors — that President Bashar Assad's government was responsible for an alleged chemical attack on civilians outside the capital of Damascus last week.
Syria's foreign minister said his country would defend itself using "all means available," while in Britain, Prime Minister David Cameron recalled Parliament to hold an emergency vote Thursday on his country's response to the alleged chemical assault. Cameron said the goal of any attack on Syria, if launched, would be to prevent the further use of chemical weapons.
French President Francois Hollande added his voice to the growing clamor for action, saying France is "ready to punish those who took the heinous decision to gas innocents."
The Arab League also threw its weight behind calls for punitive action, blaming the Syrian government for the toxic attack that activists say killed hundreds of people and calling for the perpetrators to be brought to justice. The announcement by the 22-member body, which is dominated by Gulf powerhouses Saudi Arabia and Qatar, provides indirect Arab cover for any potential military attack by Western powers.
Syrian Foreign Minister Walid al-Moallem spoke at a press conference in Damascus as condemnation of Assad's government grew over last week's purported attack with poison gas. He denied that his government was behind the attack and challenged Washington to present proof backing up its accusations.
The United Nations, meanwhile, said its team of chemical weapons experts in Syria had delayed a second trip to investigate the alleged attack near Damascus by one day for security reasons. On Monday, the team came under sniper fire.
Al-Moallem likened U.S. allegations that Assad's regime was behind the attack to false American charges that Iraq possessed weapons of mass destruction before the 2003 U.S.-led invasion of that country.
"They have a history of lies — Iraq," he said.
"We have the means to defend ourselves and we will surprise everyone," he told reporters in Damascus. "We will defend ourselves using all means available. I don't want to say more than that."
A day earlier, U.S. Secretary of State John Kerry said there was "undeniable" evidence of a large-scale chemical attack likely launched by Assad's regime.
If President Barack Obama decides to order an attack against Syria, it would most likely involve sea-launched cruise missile attacks on Syrian military and communications targets.
U.S. Defense Secretary Chuck Hagel said Tuesday that U.S. forces were now ready to act on any such presidential directive.
Hagel said the U.S. Navy had four destroyers in the eastern Mediterranean Sea positioned within range of targets inside Syria. U.S. warplanes were also in the region, he told BBC television during a visit to the southeast Asian nation of Brunei.
But any U.S. military intervention in Syria was running into fierce opposition among some members of Congress. A growing chorus of Republican and Democratic lawmakers were demanding that Obama seek congressional authorization for any strikes against the Assad regime.
In Cyprus, Defense Minister Fotis Fotiou said naval traffic in the eastern Mediterranean was very heavy with vessels from "all the major powers." He also said Cypriot authorities were making plans to deal with a possible exodus of foreign nationals from Syria.
But Charles Heyman, a former British officer who edits The Armed Forces of the UK, said the lack of a U.N. Security Council resolution authorizing the use of force against the Syrian government greatly complicates matters for the West. He said that may make it difficult for Cameron to win parliamentary backing on Thursday.
Russia, a permanent member of the Security Council, has steadfastly opposed any international action against the Syrian government, a staunch ally.
"It's clear the governments want some form of military operation, but if the Security Council doesn't recommend it, then the consensus is that it's plainly illegal under international law," Heyman said. "The only legal way to go to war is in self-defense and that claim is difficult to make."
Heyman predicted a possible three-phase campaign, with the first step — the encirclement of Syria by Western military assets in the air and the sea — already underway.
"Phase two would be a punitive strike, taking out high-value command and control targets and communications centers," Heyman said. "That could be done easily with cruise missiles from ships and aircraft. Phase three would be a massive takedown of Syrian air defenses, that would have to be done before you could take out artillery and armor, which is the key to long-term success."
In Rome, Italian Foreign Minister Emma Bonino said Italy would not back any military action against Syria unless it was authorized by the U.N. Security Council — even though it considers the chemical attack to have been a war crime.
Support for some sort of international military response is likely to grow if it's confirmed that Assad's regime was responsible for the Aug. 21 attack that the group Doctors Without Borders says killed 355 people.
Ko Colijn, director of the Clingendael Institute in the Netherlands and an analyst who specializes in multilateral military issues, said the case for intervention would be helped if the U.N. inspection team now in Syria can reach a firm conclusion about whether chemical weapons were used — and who is responsible.
If there is clarity, he said, it could lead to "a diplomatic agreement" between sparring Security Council members the United States and Russia.
In an emergency meeting Tuesday, the Arab League also called on members of the Security Council to overcome their differences and agree on "deterrent" measures against those who committed "this heinous crime."
"The council holds the Syrian regime totally responsible for this heinous crime and calls for all involved in the despicable crime to be given a fair international trial like other war criminals," the Arab League said in a statement.
Obama has yet to say how he will respond, but appeared to be moving ahead even as the U.N. expert team on the ground in Syria tried to collect evidence from the attack.
The U.N confirmed its chemical weapons team's mission faced a one-day delay Tuesday to improve preparedness and safety after unidentified snipers opened fire on the team's convoy Monday.
"The Secretary-General again urges all sides in the conflict to give safe passage and access to the team," the statement said.
In Geneva, U.N. spokeswoman Alessandra Vellucci told reporters that the U.N. inspection team might need longer than the planned 14 days to complete its work. She said its goal now is to determine what chemical weapons might have been used in the Aug. 21 attack.
"This is the first priority," she said.
Katz reported from London. Associated Press writers Zeina Karam and Bassem Mroue from Beirut, John Heilprin from Geneva, Lori Hinnant from Paris, Menelaos Hadjicostis from Cyprus and Sarah El Deeb from Cairo contributed.
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