Prospects for a quick conclusion to a U.N. investigation of a possible chemical weapons attack in Syria will depend on cooperation from the warring parties and safety for investigators — problematic conditions in the chaos of the country's civil war, an expert on weapons control told NBC News on Thursday.

Secretary-General Ban Ki-moon said Thursday that he had agreed to conduct an investigation of allegations of an attack in the northern city of Aleppo. The government and the opposition have accused each other of carrying out that attack on Tuesday.

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Ralf Trapp, a German who works on disarmament and non-proliferation issues, specializing on chemical and biological weapons, said the first job of an inspection team would be safely getting to and operating at the site. He said then -- if the Syrian parties cooperated and the inspectors felt safe — they would:

 

• Interview victims and bystanders on what they felt, smelled, saw, etc.
• Search for remnants of any weapons used. That is often difficult and unproductive, but the earlier one gets to the scene, the better.
• Take samples at the site. Pieces of weapons are rarely found, Trapp said, but the chemical agent can be uncovered in soil, plants and, if in an urban environment, bricks and building materials. Beyond the agent, inspectors will look for chemicals left behind as the agents themselves deteriorate.
• Conduct medical tests on the victims, including taking tissue samples, blood samples and, if the teams arrive quickly enough, urine samples. Samples in some cases can be analyzed on the scene, but if the inspections are delayed, there are labs in Europe and the U.S. that can find evidence in DNA and proteins.

Trapp said a big question will be how soon the UN and the Organization for the Prohibition of Chemical Weapons – of which Trapp is a former official -- can get a team into Aleppo. He said the team would have to be large and varied, with security officers and medical officers as well as inspectors.

But each day lost will influence the speed with which the investigation can be concluded, he said, because as more time elapses before biological sampling occurs, more sophisticated DNA and other toxicological testing is required. 

With optimum cooperation and conditions on the ground, an investigation led by the OPCW could be under way in days, Trapp said. A determination, including the pinpointing of the agent, could be made within days after arrival, he said -- if there is good access to interviews and environmental and biological samples. He said his former organization has equipment at the ready and could move quickly.

But if the inspection is conducted by the kind of UN group that investigated the allegations against Iraq after the 1991 Gulf War, with countries nominating experts and then gathering them, getting inspectors in could take weeks, he said. 

Considering that Aleppo is a war zone, optimum conditions are unlikely.

Trapp would not speculate on what agents were used, but he said that he has seen no reports of blistering, and without blistering, it is unlikely to have been mustard gas — although he said it’s possible that some victims might have only internal blistering.

Evidence of a nerve gas attack, for example, would be found in corpses. Victims would show certain telltale signs, like tiny pupils, saliva around the noses and eyes. There might be evidence of convulsions.

He did not dismiss the use of more common agents that are not on the proscribed list of chemical weapons. Victims said they smelled chlorine, and those felled in the attacks reported suffocating.  Chlorine, of course, is found throughout the industrial world and in large quantities can kill. Moreover, feelings of suffocation could be associated with a chlorine attack.

The chemical has a long history of use. It was the first chemical used as a weapon in World War I by German troops against French and French colonial forces. There are reports that insurgents in Iraq used chlorine in huge quantities in their attacks.

Similarly, tear gas, if used in large quantities in a confined space, can suffocate and kill.

Trapp was careful to note that even though chlorine or tear gas are not listed as prohibited weapons on the Chemical Weapons Convention, each could be considered a chemical weapon if used as a "method of warfare" rather than as being used for law enforcement or crowd control. The convention bars the use of chemicals in general as a "method of warfare." 

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UNITED NATIONS — U.N. Secretary-General Ban Ki-moon on Thursday announced that the United Nations will launch an investigation as requested by the Syrian government into allegations that chemical weapons were used in Syria.

"I have decided to conduct a United Nations investigation into the possible use of chemical weapons in Syria," Ban told reporters.

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He said the investigation will focus on "the specific incident brought to my attention by the Syrian government."

Syria asked Ban on Wednesday to investigate an alleged chemical weapons attack by "terrorist groups" near the northern city of Aleppo on Tuesday, Syrian U.N. Ambassador Bashar Ja'afari said.

The Syrian opposition said on Wednesday that there was a second chemical weapons attack on Tuesday in Damascus in addition to the one the government and opposition accuse each other of carrying out in Aleppo on the same day.

But Ban made clear that the focus of the investigation he announced would be the Aleppo attack.

"I am of course aware that there are other allegations of similar cases involving the reported use of chemical weapons," he said, adding that the United Nations would be cooperating with the Organization for the Prohibition of Chemical Weapons and the World Health Organization.

"Full cooperation from all parties will be essential. I stress that this includes unfettered access," he said. "I reiterated this point in my communications with the Syrian authorities."

"There is much work to do and this will not happen overnight. It is obviously a difficult mission," Ban said. "I intend for this investigation to start as soon as is practically possible."

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BEIRUT — Syria said Monday it is prepared to hold talks with the armed rebels bent on overthrowing President Bashar Assad, the clearest signal yet that the regime is growing increasingly nervous about its long-term prospects to hold onto power as opposition fighters make slow but persistent headway in the civil war.

The offer, by Syrian Foreign Minister Walid al-Moallem during a visit to Moscow, came hours before residents of Damascus and state-run TV reported a huge explosion and a series of smaller blasts in the capital, followed by heavy gunfire.

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State-run news agency SANA said there were multiple casualties from the explosion, which it said was a suicide car bombing.

The proposal marked the first time that a high-ranking regime official has stated publicly that Damascus would be willing to meet with the armed opposition. But al-Moallem did not spell out whether rebels would first have to lay down their weapons before negotiations could begin — a crucial sticking point in the past.

The regime's proposal is unlikely to lead to talks. The rebels battling the Syrian military have vowed to stop at nothing less than Assad's downfall and are unlikely to agree to sit down with a leader they accuse of mass atrocities.

But the timing of the proposal suggests the regime is warming to the idea of a settlement as it struggles to hold territory and claw back ground it has lost to the rebels in the nearly 2-year-old conflict.

Opposition fighters have scored several tactical victories in recent weeks, capturing the nation's largest hydroelectric dam and overtaking airbases in the northeast. In Damascus, they have advanced from their strongholds in the suburbs into neighborhoods in the northeast and southern rim of the capital, while peppering the center of the city with mortar rounds for days.

Monday night's explosion struck about 800 yards from Abbasid Square, a landmark plaza in central Damascus. It was followed by several other smaller blasts thought to be mortar shells landing in various districts of the capital. The blasts and subsequent gunfire caused panic among residents who hid in their apartments.

Shifting momentum
On Thursday, a car bomb near the ruling Baath Party headquarters in Damascus killed at least 53 people, according to state media.

While the momentum appears to be shifting in the rebels' direction, the regime's grip on Damascus remains firm, and Assad's fall is far from imminent.

Still, Monday's offer to negotiate with the armed opposition — those whom Assad referred to only in January as "murderous criminals" and refused to talk with — reflects the regime's realization that in the long run, its chances of keeping its grip on power are slim.

Asked about al-Moallem's remarks, U.S. State Department spokesman Patrick Ventrell said the offer of talks was a positive step "in the context of them raining Scuds down on their own civilians." But he expressed caution about the seriousness of the offer.

"I don't know their motivations, other than to say they continue to rain down horrific attacks on their own people," Ventrell told reporters in Washington. "So that speaks pretty loudly and clearly."

If the Assad regime is serious, he said, it should inform the U.N. peace envoy, Lakhdar Brahimi of its readiness for talks. Ventrell said the regime hasn't done that yet.

Andrew Tabler, a fellow at the Washington Institute, said called the offer "a sign of weakness."

"I think everybody knows, including Bashar Assad, that they (the regime) can't hang onto the whole country," Tabler said.

Mustafa Alani, an analyst with the Gulf Research Center in Geneva, said the regime has "reached the conclusion that they are heading toward a major defeat eventually, and this is the right time to negotiate."

"They are not losing miles every day, but they are losing substantial ground every day. So the regime is not genuine (in its offer) because it has changed, it's genuine because it is responding to a major shift in the balance of power on the ground," he added.

Alani cautioned, however, that the regime is also eager to keep the idea of talks alive in order to forestall any Western decision on arming the rebels. As long as the possibility of negotiations is still on the table, the United States and the European Union — which have so far provided only non-lethal aid — will be reluctant to open the flood gates on weapons for the opposition, he said.

Strategic delays?
"The whole regime tactic is to delay supplying arms, to buy time," Alani said. "The regime can show good will. Whether they're a viable partner or not is a different story."

It's also unclear who exactly the regime would sit across from at the negotiating table.

The dozens of armed groups across Syria fall under no unified command and do not answer to the Syrian National Council, an umbrella group of opposition parties that the West recognizes as the legitimate representative of the Syrian people.

At least one group offered a lukewarm response Monday to al-Moallem's proposal.

The head of one group, Free Syrian Army chief Gen. Salim Idriss, said he is "ready to take part in dialogue within specific frameworks," but then rattled off conditions that the regime has rejected in the past.

"There needs to be a clear decision on the resignation of the head of the criminal gang, Bashar Assad, and for those who participated in the killing of the Syrian people to be put on trial," Idriss told pan-Arab broadcaster Al-Arabiya TV.

He said the government must agree to stop all kinds of violence and to hand over power, saying that "as rebels, this is our bottom line."

Syria's 23-month-old conflict, which has killed more than 70,000 people and destroyed many of the country's cities, has repeatedly confounded international efforts to bring the parties together to end the bloodshed. Russia, a close ally of Assad and his regime's chief international advocate, offered Feb. 20, in concert with the Arab League, to broker talks between the rebels and the government.

With the proposal, which the Kremlin would be unlikely to float publicly without first securing Damascus' word that it would indeed take part, Moscow ratcheted up the pressure on Syria to talk to the opposition.

Russia Syrian situation 'at a crossroads'
Russia has shielded Assad's government from U.N. action and kept shipping weapons to the military, but it is growing increasingly difficult to protect the regime as the violence grinds on.

Russian Foreign Minister Sergey Lavrov repeated his call Monday for Syria to negotiate with the opposition, saying before meeting al-Moallem that "the situation in Syria is at a crossroads now." He also warned that further fighting could lead to "the breakup of the Syrian state."

Past government offers for talks with the opposition have included a host of conditions, such as demanding that the rebels first lay down their arms. Those proposals have been swiftly rejected by both activists outside Syria and rebels on the ground.

Both sides in the conflict in recent weeks have floated offers and counteroffers to hold talks on the crisis.

In a speech in January, Assad offered to lead a national dialogue to end the bloodshed, but said he would not talk with the armed opposition and vowed to keep fighting. The opposition rejected the proposal.

This month, the leader of the Syrian National Coalition, the umbrella group for opposition parties, said he would be open to discussions with the regime that could pave the way for Assad's departure, but that the government must first release tens of thousands of detainees. The government refused, and even members within the coalition balked at the idea of talks.

Speaking to reporters Monday in Cairo, SNC chief Mouaz al-Khatib accused the regime of procrastinating and said it had derailed his dialogue offer by not responding to the coalition's conditions.

"We are always open to initiatives that stop the killing and destruction, but the regime rejected the simplest of humanitarian conditions. We have asked that the regime start by releasing women prisoners and there was no response," he said. "This regime must understand that the Syrian people do not want it anymore."

Reversal on Rome meeting
The coalition also finds itself at odds with its Western backers. Initially, it said it would boycott a conference in Rome that is to help drum up financial and political support for the opposition. The SNC said it had suspended its participation in the Rome meeting because of the indifference of the West and the coalition's Arab allies over the regime's attacks on the Syrian people.

Walid al-Bunni, a spokesman for the Coalition, said later Monday that the group has reversed its decision following a phone call between al-Khatib and U.S. Secretary of State John Kerry.

Al-Bunni told Al-Arabiya TV the decision was made based on guarantees al-Khatib heard from western diplomats that the conference would be different this time. He did not elaborate.

Kerry on Monday urged rebel leaders not to skip the meeting and insisted that more help is on the way.

Kerry made a public plea at a joint news conference with British Foreign Secretary William Hague and also called al-Khatib, leader of the Syrian Opposition Council, "to encourage him to come to Rome," a senior U.S. official said. The official spoke on condition of anonymity because he wasn't authorized to speak publicly on the matter.

Meanwhile, the fighting inside Syria rages on.

The Syrian Observatory for Human Rights activist group reported heavy clashes Monday near a police academy in Khan al-Asal just outside Aleppo.

Rebels backed by captured tanks launched an offensive on the facility Sunday. Observatory director Rami Abdul-Rahman said at least 13 rebels and five regime troops were killed.

In another part of Aleppo, rebels downed a military helicopter near the Mennegh airport, where there have been fierce clashes for months.

A video posted online by activists showed a missile being fired, a trail of white smoke and the aircraft going up in flames. Voices in the background shouted, "God is great!" as a man raised both hands in celebration.

The video appeared to be authentic and corresponded to other AP reporting.

The main Syrian opposition grouping has said it turned down invitations to visit Washington and Moscow to protest what it described as international silence over destruction of the ancient city of Aleppo by Syrian missile strikes.

A statement late on Friday by the Syrian National Coalition, an umbrella group of opposition political forces, said it also had suspended participation in a Friends of Syria conference of international powers due in Rome next month to protest the attacks it said have caused many civilian casualties.

"Hundreds or civilians have been killed by Scud missile strikes. Aleppo, the city and the civilization, is being destroyed systematically," the statement said.

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"The Russian leadership especially bears moral and political responsibility for supplying the regime with weapons," it added, referring to Moscow's status as a leading ally of Syrian President Bashar Assad.

"In protest of this shameful international stand, the coalition has decided to suspend its participation in the Rome conference for the Friends of Syria and decline the invitations to visit Russia and the United States."

The invitations had been extended to opposition coalition leader Mouaz Alkhatib after he met the Russian and U.S. foreign ministers in Munich this month.

The invitations were made shortly after Alkhatib offered to negotiate Assad's departure with members of the Syrian government who were not tainted by having participated in the crackdown on the 23-month-long revolt.

Rocket attacks on eastern districts of Aleppo, Syria's industrial and commercial hub, killed at least 29 people on Friday and trapped a family of 10 in the ruins of their home, opposition activists in the city said.

On Tuesday activists said at least 20 people were killed when a large missile hit the rebel-held district of Jabal Badro, also in the east of the contested city.

Reuters

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BEIRUT — At least 65 people, apparently shot in the head, were found dead with their hands bound in a district of the northern Syrian city of Aleppo on Tuesday, a pro-opposition monitoring group said.

The U.K.-based Syrian Observatory for Human Rights said the death toll could rise as high as 80 in what it called a "new massacre."

It was not clear who carried out the killings.

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Photos posted online by activists showed the muddied bodies of about a dozen men lying by a small river in what they said was the Bustan al-Qasr neighborhood of Aleppo.

Close-up shots of some of the corpses showed they had what appeared to be gunshot wounds to the head.

Government forces and rebels in Syria have both been accused by human rights groups of carrying out summary executions in the 22-month-old conflict, which has claimed more than 60,000 lives.

Rebels pushed into Aleppo, Syria's most populous city, over the summer, but have been stuck in a stalemate with government forces. The city is divided roughly in half between the two sides.

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ALEPPO, Syria -- In Syria's once-affluent merchant city of Aleppo, a 60-year-old man wrapped in several layers of clothes lines up alongside his shivering grandchildren for bread -- a daily and often fruitless ritual that consumes most of his day.

Shielding himself from the rain in Bustan al-Qasr, a rebel-held district in the southwest of Syria's biggest city, Alaa el-Din Hout says shortages of food and fuel are driving his family and many other residents to desperation.

"We're starving. I can bear it but what about my children? I stand from 3 in the afternoon until 11 at night and you can't always get bread," said Hout, wearing a winter hat and scarf to keep out the winter cold.

"We're reduced to either begging or stealing."

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Five months after rebels brought their fight against President Bashar al-Assad into the heart of Aleppo, the eastern and southern swathes of the city are a mishmash of deserted districts and no-man's land.

Rebel fighters have hunkered down in warehouses to halt offensives by Assad's forces in the civil war. The few lucky bakeries in Aleppo that have supplies often have hundreds standing in line, hoping for a few loaves.

Abu Abdo, Hout's son-in-law, has three children, the youngest a 2-month-old baby shivering underneath wraps of blankets. "This is the hardest period I've ever gone through. There's no work, no industry, no electricity, no diesel. How will people live?" said the former stonemason.

"The people have a right to demand their freedom, that's the least of the demands -- I am for the downfall of the regime."

The summer battles around Aleppo have subsided but Syrians in this city, whose peacetime population of 2.5 million has been reduced by an exodus of hundreds of thousands, are facing new challenges of winter cold and wartime shortages. 

Some districts are faring better, with vegetable sellers laying out tomatoes and tangerines and falafel shops frying the ubiquitous bean food. But many people are too poor to afford it.

"We can't find any bread. There's a famine. People are dying, half the bakeries are closed. There's no flour," said one man in al-Sha'ar district.

Ahmed, a 42-year-old man with six children, said he queued from 8 in the morning. "Sometimes we get bread, sometimes we don't. There's no water, no gas, no electricity. The water supply runs out every two days."

Not all the city's residents hold Assad responsible for their suffering. Aleppo has traditionally been a city with divided loyalties and even in areas controlled by the rebels, some people have had enough of the daily shortages and blame them on the president's opponents.

Related: Syria fires more Scud missiles at rebels

"We don't leave our homes after 6 p.m. We just want peace again," said Um Saleh, a woman wearing a face veil and a full-length black wool coat. She blamed the Free Syrian Army rebels for hijacking bread lines to take loaves for their family.

Her husband Abu Saleh said "mistakes" had been made by Assad's officials but added: "You can't fix wrong with wrong."

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