President Barack Obama bluntly warned Syrian President Bashar al-Assad on Monday not to cross a "red line" by using chemical or biological weapons in his country's bloody conflict and suggested that such action would prompt the United States to consider a military response.
Pointing out that he had refrained "at this point" from ordering US military engagement in Syria, Obama said that there would be "enormous consequences" if Assad failed to safeguard his weapons of mass destruction.
It was Obama's strongest language to date on the issue, and he warned Syria not only against using its unconventional weapons, but against moving them in a threatening fashion.
"We have been very clear to the Assad regime, but also to other players on the ground, that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized," Obama said. "That would change my calculus."
"We cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people," Obama told an impromptu White House news conference.
He acknowledged he was not "absolutely confident" the stockpile was secure.
Obama said the issue was of concern not only to Washington, but also to its close allies in the region, including Israel.
Seeking re-election in November, Obama has been reluctant to get the United States involved in another war in the Middle East, even refusing to arm rebels fighting a 17-month-old uprising against Assad.
Syria last month acknowledged for the first time that it had chemical and biological weapons and said it could use them if foreign countries intervene — a threat that drew strong warnings from Washington and its allies.
Western countries and Israel have expressed fears chemical weapons could fall into the hands of militant groups as Assad's authority erodes.
Israel has said that if Syrian-backed Hezbollah guerrillas used the situation to take control of the weapons, it would "act immediately and with utmost force".
"We're monitoring that situation very carefully. We have put together a range of contingency plans," Obama said when asked whether he envisioned the possibility of using US forces at least to safeguard Syria's chemical arsenal.
The Global Security website, which collects published intelligence reports and other data, said there were four suspected chemical weapons sites in Syria: north of Damascus, near Homs, in Hama and near the Mediterranean port of Latakia. Weapons it produces include the nerve agents VX, sarin and tabun, it said, without citing its sources.
Obama also used the opportunity to renew his call for Assad to step down.
"The international community has sent a clear message that rather than drag his country into civil war, he should move in the direction of a political transition," Obama said. "But at this point, the likelihood of a soft landing seems pretty distant."
Obama said the United States had already provided US$82 million in humanitarian assistance for Syria refugees and "we'll probably end up doing a little bit more" to keep the situation from destabilizing Syria's neighbours.
AIR STRIKES KILL 100
Government forces pummelled the battered city of Aleppo with airstrikes and tanks and shelled parts of Damascus and southern Syria Monday (local time), killing at least 100 people during a major Muslim holiday, rights groups and activists said.
The violence escalated dramatically after a one-day lull on Sunday, the start of the three-day Eid al-Fitr holiday which marks the end of the holy month of Ramadan.
The renewed fighting showed President Bashar Assad's regime is not letting up on its drive to quell the 17-month-old uprising out of respect for the occasion.
The discovery of bodies in similar condition is not uncommon in Syria, particularly in the last few months as the uprising descended into a civil war with heavy sectarian undertones.
Most of the deaths Monday were a result of tank and mortar shelling as well as clashes in the Damascus suburbs of Daraya and Moadamiyeh, where some activists reported the regime used helicopter gunships. The Observatory and others said up to 31 people were killed.
An activist, El-Said Mohammed, said some 30 troops along with a tank defected to the rebels' side in Moadamiyeh on Sunday, which may have been the reason for Monday's shelling.
Mohammed spoke by Skype from the Damascus area. His information could not be verified.
Both the Observatory, which relies on a network of activists on the ground, and the LCC, reported at least 100 civilian deaths across the country, a heavy toll for a single day. Anti-regime activists say some 20,000 people have been killed since the revolt against Assad's rule began in March 2011.
The rights groups and activists said the latest assaults by tanks and warplanes caused two houses to collapse in Aleppo, Syria's largest city, killing at least 14 people. The buildings were in the Al-Sakhour and Qadi Askar neighbourhoods, said activist Mohammed Saeed, reached by Skype inside the city. The reports could not be independently confirmed.
Aleppo has been the scene of daily battles for several weeks now, with forces loyal to Assad trying to wrest control from the rebels without making much headway.
In the southern city of Daraa, birthplace of the uprising, intense fighting between government troops and rebels killed 16 people, including two children and two women, the activist groups said.
As it battles for survival against the rebels, the regime has increasingly resorted to the use of airstrikes, particularly in the north around Aleppo where rebels have seized large swathes of territory.
Fighter jets on Monday bombed the town of Tel Rifat, 30 kilometres north of Aleppo. The town serves as the headquarters of one of the largest rebel groupings.
The bombing punched a crater six feet deep in the courtyard of a high school and vocational school for girls and levelled five nearby homes. An adjacent elementary and middle school for girls was also damaged, apparently by strafing from fighter jets.
No one was killed or injured in the airstrike, residents said, because the school and the homes were empty. Most of the town's 35,000 people have fled due to frequent airstrikes and shelling. The same spots were bombed on August 8.
Residents said they didn't know why the area was targeted. The Brigade of Unification, the largest rebel grouping fighting in Aleppo province which has its headquarters in the town, has never been directly targeted by government forces.
"They don't want there to be an educated society," said Hatem, who taught Islamic education at the school and came to inspect the damage. "They want people to be ignorant so they don't ask for their rights."
He said two others schools in town had been damaged in previous government strikes. He declined to give his full name for fear for retribution.
The UN's new envoy to Syria acknowledged on Sunday that he had no concrete ideas to end the conflict and that his mission would be difficult without a unified position by the UN Security Council.
"The problem is not what I can do differently, it is how others are going to behave differently," Lakhdar Brahimi told The Associated Press at his Paris home on Sunday.
"If they spoke in one voice and were clearly supportive of what I will be doing on their behalf, that is what I need," Brahimi said of what he seeks from the Security Council.
"Without a unified voice from the Security Council, I think it will be difficult," the former Algerian foreign minister added.
Brahimi was named Friday to replace former U.N. Secretary-General Kofi Annan as peace envoy to Syria. He served as a UN envoy in Afghanistan and Iraq and helped negotiate the end of Lebanon's civil war as an Arab League envoy.
He said Annan's mission failed "because the international community was not as supportive as he needed them to be."
Russia and China have used their veto power at the Security Council to block strong Western- and Arab-backed action against the regime of Syria's Assad.
A Syrian foreign ministry source quoted by the official SANA news agency warned Brahimi that, for his mission to succeed, he must persuade countries backing the rebels to stop their support for the "armed terrorist bands" - the regime's parlance for the rebels.
Syria often singles out Saudi Arabia, Qatar and Turkey as the rebels' main backers.