In recent weeks, thousands of Syrians have recorded personal appeals to members of Congress and the American public urging them to oppose an airstrike, though it is not clear whether those efforts are coordinated with their government. 
 
 For the rebels, who could often use a tip or two in the area of public relations, all of this is unqualified bad news. “It is disappointing,” said Najib Ghadbian, the main Syrian opposition group’s special representative to the United States. “If the regime wants to play with this, it could take months or years. This is why we need accountability.” 
 
 A rebel brigade commander named Moaz al-Yousef, reached by telephone, spoke bitterly of Mr. Obama’s interest in the Russian proposal — and the delay of the Congressional votes — as a betrayal. 
 
 “We had hopes, it was a dream, and now it’s gone and we feel disappointed,” he said. “We should completely cut off our relationship with him — Obama has completely lost his credibility.” 
 
 The rebels’ foreign backers were almost equally derisive. Recep Tayyip Erdogan, the Turkish prime minister, dismissed the Russian proposal in a speech in Istanbul on Thursday, saying that Mr. Assad was merely buying time for “new massacres.” 
 
 In his interview with Russian television, Mr. Assad hinted at another possible stumbling block in the prospective chemical weapons agreement by saying Israel should ratify it first. Israel has signed the accord but not ratified it, and is extremely unlikely to do so in light of the difficulty of verifying Syrian compliance in the midst of a civil war. 
 
 For Mr. Assad, the Russian proposal comes as a welcome reprieve. Even before the chemical weapons attack on Aug. 21, his military was effectively locked in a stalemate with the opposition, despite the intervention of militia fighters from Hezbollah, the Lebanese Shiite movement, in recent months. Although Mr. Assad won a few important victories, he has still not pushed the rebels from the Damascus suburbs. That, many analysts say, was the goal of the chemical weapons attack, in a rebel-held part of the eastern suburb of Ghouta. ||||| GENEVA — Secretary of State John Kerry planned to meet Friday evening with his Russian counterpart, as the two sides sought to forge an agreement on how to disarm Syria’s chemical weapons program. 
 
 Mr. Kerry and Sergey Lavrov, the Russian foreign minister, held a working lunch earlier on the chemical weapons issue. Their teams of arms controls officials also conferred. In the morning, Mr. Kerry and Mr. Lavrov had a three-way meeting with Lakhdar Brahimi, the United Nations envoy, on the parallel issue of how to arrange a peace conference to facilitate a political settlement. 
 
 “President Obama is deeply committed to a negotiated solution with respect to Syria,” Mr. Kerry told a joint news conference at which he said the three diplomats would continue their discussions around Sept. 28 in New York. 
 
 But prospects for peace talks, he said, would depend heavily on the outcome of the efforts to put Syria’s chemical weapons under international control and eventually destroy them. 
 
 “We both agreed to do that homework and meet again in New York around the time of the U.N. General Assembly in order to see if it is possible then to find a date for that conference, much of which will obviously depend on the capacity to have success here in the next days″ on the subject of the chemical weapons, Mr. Kerry said. It was not clear if their Geneva meetings would wrap up Friday or continue into Saturday. 
 
 As the deliberations went on, Kofi Annan, the former United Nations Secretary General and prior Syrian envoy, also conferred separately with Mr. Kerry and Mr. Lavrov. 
 
 “These are fast-moving developments,” said Mr. Annan. “And I hope we are going to see further movement on the issue.” 
 
 “Hopefully at the end of the day we will come up with a proposal that deals effectively with the chemical weapons, gets people back to the table to seek political settlement and improve the humanitarian condition for the people of Syria.” 
 
 The State Department announced that Mr. Kerry would also be traveling to Jerusalem on Sunday to meet with Benjamin Netanyahu, the Israeli prime minister. Mr. Kerry met recently in London with Mahmoud Abbas, the president of the Palestinian Authority, and one purpose of his meeting in Israel is to discuss the Middle East peace talks. 
 
 But Jen Psaki, the spokesman for the State Department, said the meeting with Mr. Netanyahu would also focus on developments in Syria. 
 
 Mr. Kerry has argued strongly in recent weeks that it was necessary to carry out a military strike in Syria after the Aug. 21 chemical weapons attack near Damascus to reinforce the message to Iran that the Obama administration would not allow the Iranians to field a nuclear device and was retaining a military option as a last resort. 
 
 After Jerusalem, Mr. Kerry plans meet on Monday in Paris with Laurent Fabius, the French foreign minister, and William Hague, the British foreign secretary. The Monday meeting was first reported by Agence France-Presse and was confirmed by an American official. 
 
 That would provide Mr. Kerry with an opportunity to confer with the United States’ two principal European allies on the Syria crisis, each of whom is a permanent member of the United Nations Security Council. 
 
 While in Paris, Mr. Kerry will also meet with Saudi Foreign Minister Saud al-Faisal. Saudi Arabia has been a strong supporter of the Syrian opposition and advocate of taking tough action following the August 21 chemical weapons attack. 
 
 Mr. Obama’s decision to defer military action, however, has stirred concern in Israel that the credibility of the American policy toward Iran is being eroded. 
 
 Mr. Kerry was not the only one here who spoke publicly on Friday about the possibility of holding peace talks on Syria. 
 
 Sitting on a dais with Mr. Kerry, Mr. Lavrov hailed effort of the Russian president, Vladimir V. Putin, to persuade President Bashar al-Assad of Syria to join the treaty banning chemical arms, and stressed the need to resume peace talks in Geneva. 
 
 Mr. Lavrov said it was “very unfortunate that for a long time the Geneva communiqué was basically abandoned,” referring to a 2012 document that outlined basic terms for the peace talks. 
 
 Despite the public facade of unity, however, the United States and Russia have been sharply divided over how to organize a political settlement and who should attend a peace conference. ||||| Anwar Amro/Agence France-Presse/Getty Images A fighter allied to the government of Syrian President Bashar al-Assad ran across a street in Damascus following fighting with rebel forces on Thursday. 
 
 A secretive Syrian military unit at the center of the Assad regime's chemical weapons program has been moving stocks of poison gases and munitions to as many as 50 sites to make them harder for the U.S. to track, according to American and Middle Eastern officials. 
 
 The movements of chemical weapons by Syria's elite Unit 450 could complicate any U.S. bombing campaign in Syria over its alleged chemical attacks, officials said. It also raises questions about implementation of a Russian proposal that calls for the regime to surrender control of its stockpile, they said. 
 
 U.S. and Israeli intelligence agencies still believe they know where most of the Syrian regime's chemical weapons are located, but with less confidence than six months ago, U.S. officials said. 
 
 Secretary of State John Kerry met Thursday in Geneva with his Russian counterpart to discuss a road map for ending the weapons program. The challenges are immense, Mr. Kerry said. 
 
 WSJ Exclusive: A secret Syrian military unit is spreading stockpiles of poisonous gas and munitions to make tracking by the U.S. harder. WSJ Pentagon correspondent Julian Barnes explains. Photo: AP. 
 
 The U.S. alleges a chemical-weapons attack by the Syrian government on Aug. 21 killed more than 1,400 people, including at least 400 children. Syrian President Bashar al-Assad on Thursday again denied any involvement in a chemical attack, but he said his government was prepared to sign an agreement banning the use of chemical weapons. Syrian officials couldn't immediately be reached for comment on the weapons. 
 
 Unit 450—a branch of the Syrian Scientific Studies and Research Center that manages the regime's overall chemicals weapons program—has been moving the stocks around for months, officials and lawmakers briefed on the intelligence said. 
 
 Movements occurred as recently as last week, the officials said, after Mr. Obama said he was preparing to launch strikes. 
 
 Enlarge Image Close Reuters A man affected by what activists say was nerve gas received assistance in the Damascus suburbs last month. 
 
 The unit is in charge of mixing and deploying chemical munitions, and it provides security at chemical sites, according to U.S. and European intelligence agencies. It is composed of officers from Mr. Assad's Alawite sect. One diplomat briefed on the unit said it was Alawite from "janitor to commander." 
 
 U.S. military officials have looked into the possibility of gaining influence over members of Unit 450 through inducements or threats. "In a perfect world, you would actually like to co-opt that unit. Who cares who pays them as long as they sit on the chemical weapons," said a senior U.S. military official. 
 
 Although the option remains on the table, government experts say the unit is so close-knit that they doubt any member could break ranks without being exposed and killed. 
 
 The U.S. estimates the regime has 1,000 metric tons of chemical and biological agents. "That is what we know about. There might be more," said one senior U.S. official. 
 
 The regime traditionally kept most of its chemical and biological weapons at a few large sites in western Syria, U.S. officials said. But beginning about a year ago, the Syrians started dispersing the arsenal to nearly two dozen major sites. 
 
 Unit 450 also started using dozens of smaller sites. The U.S. now believes Mr. Assad's chemical arsenal has been scattered to as many as 50 locations in the west, north and south, as well as new sites in the east, officials said. 
 
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 The U.S. is using satellites to track vehicles employed by Unit 450 to disperse the chemical-weapons stocks. But the imagery doesn't always show what is being put on the trucks. "We know a lot less than we did six months ago about where the chemical weapons are," one official said. 
 
 The movements, activities and base locations of Unit 450 are so sensitive that the U.S. won't share information with even trusted allies in the opposition for fear the unit would be overrun by rebels, said current and former U.S. officials. 
 
 The U.S. wants any military strikes in Syria to send a message to the heads of Unit 450 that there is a steep price for following orders to use chemical weapons, U.S. officials said. 
 
 At the same time, the U.S. doesn't want any strike to destabilize the unit so much that it loses control of its chemical weapons, giving rebels a chance to seize the arsenal. 
 
 "Attacking Unit 450, assuming we have any idea where they actually are, would be a pretty tricky affair because…if you attack them you may reduce the security of their weapons, which is something we certainly don't want," said Jeffrey White, a veteran of the Defense Intelligence Agency and a defense fellow at The Washington Institute. 
 
 Within Syria, little is known about Unit 450 or the Syrian Scientific Studies and Research Center. One of the buildings is in a sprawling complex on the outskirts of Damascus. 
 
 Even high-ranking defectors from the Syrian military that form the core of the rebel insurgency—including those who served in units trained to handle chemical attacks—said they hadn't heard of Unit 450. 
 
 The Pentagon has prepared multiple target lists for possible strikes, some of which include commanders of Unit 450. 
 
 But a senior U.S. official said no decision has been made to target them, reflecting the challenge of sending a message to Unit 450 without destabilizing it. 
 
 In some respects, officials said, the hands-on role that Unit 450 plays in safeguarding the regime's chemical weapons secrets makes it too valuable for the U.S. to eliminate, even though the U.S. believes the unit is directly responsible for the alleged chemical weapons abuses. 
 
 The Syrian Scientific Studies and Research Center answers only to Mr. Assad and the most senior members of his clan, according to U.S. and European officials. Attack orders are forwarded to a commanding officer within Unit 450. 
 
 If the Russians clinch a deal for Mr. Assad to give up his chemical weapons, any prospective United Nations-led force to protect inspectors and secure storage sites would likely need to work closely with Unit 450 and the research center, current and former administration officials said. 
 
 Gen. Martin Dempsey, the chairman of the U.S. military's Joint Chiefs of Staff, has said that President Barack Obama directed him to plan for "a militarily significant strike" that would deter the Assad regime's further use of chemical weapons and degrade the regime's military capability to employ chemical weapons in the future. 
 
 But officials said the U.S. doesn't plan to bomb chemical weapons sites directly because of concerns any attack would disperse poison agents and put civilians at risk. 
 
 In addition to satellites, the U.S. also relies on Israeli spies for on-the-ground intelligence about the unit, according to U.S. and Israeli officials. 
 
 Though small in size, Unit 450 controls a vast infrastructure that makes it easier for the U.S. and Israel to track its movements. Chemical weapons storage depots are guarded by the unit within larger compounds to provide multiple layers of security, U.S. officials said. 
 
 Whenever chemical munitions are deployed in the field, Unit 450 has to pre-deploy heavy equipment to chemical mixing areas, which the U.S. and Israel can track. 
 
 Write to Adam Entous at adam.entous@wsj.com, Julian E. Barnes at julian.barnes@wsj.com and Nour Malas at nour.malas@dowjones.com 
 
 A version of this article appeared September 13, 2013, on page A1 in the U.S. edition of The Wall Street Journal, with the headline: Elite Syrian Unit Scatters Chemical Arms Stockpile. ||||| Story highlights U.N.-Arab League calls the Kerry, Lavrov talks "extremely important" 
 
 A Russian spokesman says U.S. is "unaccustomed" to competition 
 
 Official: Two sides are "closer to agreement" on scope of Syria's chemical weapons 
 
 Even as they trade barbs publicly -- and even as artillery shells and accusations continue to fly in Syria -- the United States and Russia could take solace Friday in at least one respect: They are still talking. 
 
 Discussions between the two in Geneva -- centered around Moscow's proposal to have Syrian President Bashar al-Assad's government hand over its chemical weapons stockpile -- were supposed to end Friday. They continued through the night and were extended into Saturday for a reason, U.S. officials said. 
 
 "If there was no opening, we wouldn't still be here," a senior State Department official said. 
 
 An Obama administration official said separately that "we are coming closer to agreement on the scope of Syria's chemical weapons stockpile." 
 
 And even before the Geneva talks' extension was announced, U.S. Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov signaled their intent to meet again: on September 24 in New York on the sidelines of the U.N. General Assembly. 
 
 The prospect of yet another round of negotiations in the next few weeks pointed to a potentially bigger endgame for the United States and Russia in the hastily arranged meeting they began on Thursday in the Swiss city. 
 
 That's not to say all of the many outstanding issues -- on Syria's chemical weapons and much more -- have been resolved. 
 
 Senior U.S. administration officials told reporters on condition of not being identified the main sticking point was what consequences al-Assad and his government should face. 
 
 These officials have no expectations Russia would agree to any U.N. resolution that included authorization for possible military force against Syria. The United States, therefore, will not insist it be included. 
 
 That runs counter to Obama's call for the international community to take action, including a potential military strike, for what the United States and allies call a chemical weapons attack by al-Assad's forces last month outside Syria's capital that they say killed more than 1,400 people. 
 
 Obama has threatened to act alone, if necessary, and his administration credits that threat with Russia's surprise proposal last week to have Syria turn over its chemical weapons arsenal to international control. 
 
 Outside of the United Nations, however, administration officials insisted they would not take the military threat off the table. 
 
 A senior defense official said there has been "no change" in the military's planning or readiness levels and commanders have not been instructed to change their "posture" in any way. 
 
 Chemical weapons report expected Monday 
 
 The United Nations -- and especially its Security Council, including permanent members the United States, Russia, China, France and Britain -- could play a key role in the international community's response to Syria. And a report by its inspectors looking into an August 21 chemical weapons attack outside Damascus could be pivotal in guiding where countries come down on the issue. 
 
 U.N. Secretary-General Ban Ki-mooon is expected to present the report to the Security Council at 11 a.m. Monday, three diplomatic sources said. Ban said Friday that he believes it "will be an overwhelming report that chemical weapons were used." 
 
 The big questions are by whom and, if that's settled, what the world should do about it. 
 
 Al-Assad and other Syrian officials have vehemently denied their forces were responsible, despite assertions by Obama and others to the contrary. 
 
 Russia has stood by its longtime ally Syria, challenging the validity of the U.S. claims. At the same time, and as the threat of U.S.-led strikes loomed, Moscow raised its proposal on Syria's chemical weapons stockpiles and working through the U.N. -- this after, time and again, blocking U.N. action involving Syria. 
 
 Al-Assad quickly agreed, leading to the talks between Kerry and Lavrov in Geneva that began Thursday. Syria also told the United Nations on Thursday that it has sent the paperwork for joining the Chemical Weapons Convention, which bans such armaments. 
 
 The Syrian submission was being reviewed by U.N. lawyers. If deemed sufficient, Secretary-General Ban Ki-moon would register it and Syria would officially be a member state in the convention. 
 
 U.N. envoy: U.S.-Russia talks 'extremely important' 
 
 At first, the Geneva talks were about Russia's proposal Monday for Syria to give up control of its chemical weapons, which the United States had demanded in order for Obama to drop plans to launch military strikes. 
 
 Now the stakes have gotten higher, with Kerry telling reporters that progress in the broader peace process will largely depend on whether the current Geneva negotiations on Syria's chemical weapons succeed. 
 
 A communique from last year's Syrian peace talks attended by all parties called for a ceasefire and establishing a fully inclusive transitional government to write a new constitution. 
 
 That went nowhere, however. In fact, the U.N. estimates more than 100,000 people have been killed since the civil war began in 2011, in addition to more than 2 million becoming refugees and over 4 million being displaced within Syria. 
 
 Lakhdar Brahimi, the joint U.N.-Arab League envoy on Syria, expressed fresh hopes Friday that a peaceful, political solution to end the war could be reached. Kerry and Lavrov's talks were a big reason for his optimism, with Brahimi calling them "extremely important" -- not regarding chemical weapons, but for the peace process generally. 
 
 'A criminal act' 
 
 To keep up pressure on al-Assad, Obama on Friday described last month's chemical weapons attack a "criminal" act. Ban weighed in as well, saying the Syrian leader "has committed many crimes against humanity, and therefore I am sure there will be surely a process of accountability when everything is over." 
 
 U.S. officials say the mere existence of talks with Russia on the matter is progress, noting that such a prospect would not have been considered just a week ago due to Moscow's repeated efforts to block U.N. action against Syria. 
 
 Speaking to reporters Friday after he and Lavrov met with Brahimi, Kerry called the talks about Syria's chemical weapons "constructive." 
 
 "We are working hard to find common ground to be able to make that happen. And we discussed some of the homework that we both need to do," Kerry said. 
 
 Lavrov said Russia had promoted a peaceful solution to Syria's civil war, adding that the communique agreed to in last year's first round of peace talks involving all the parties had been "basically abandoned." 
 
 President Barack Obama addressed the nation about Syria on Tuesday. 
 
 On chemical weapons, Lavrov said international officials had to work together "to design a road which would make sure that this issue is resolved quickly, professionally, as soon as practical." 
 
 Getting chemical weapons fraught with challenges 
 
 Even if all parties agree, weapons experts say the already major challenge of putting Syria's chemical stockpile under international control would be extremely difficult, if not impossible, amid an active civil war. 
 
 Syria this week acknowledged that it possesses chemical weapons and wants to join the global convention that bans them. 
 
 CNN's Nick Paton Walsh reports that the convention would become legally binding on Syria 30 days after it formally joins, meaning al-Assad's government would have to permit inspections at that time. 
 
 After another 30 days -- which would be 60 days from when it formally joined the convention -- Syria would have to declare its chemical weapons stockpiles. 
 
 On Thursday, al-Assad noted that joining the convention would give Syria the standard 30 days from compliance to declare its stockpiles, but Kerry responded by expressing concern about that long a time period, saying "we believe there is nothing standard about this process." 
 
 At the State Department on Friday, spokeswoman Marie Harf said that "verifying, accounting for securing and destroying a large stockpile of chemical weapons takes time," adding that "it's very difficult to do, particularly in an active war zone." 
 
 "If we keep forward momentum, if we believe there's a credible and verifiable plan on the table to do just that, we'll keep moving forward with that process, because resolving this issue diplomatically is certainly preferable to resolving it or to dealing with it with military action," Harf said. 
 
 Political hurdles 
 
 Obama had tried to put together a NATO coalition to attack Syria, but the British Parliament voted against taking part, denying him a normally reliable ally. Other allies said they wanted U.N. authorization in the form of a Security Council resolution before they would join a coalition. 
 
 The president then asked Congress to authorize a military response in Syria but appeared in danger of losing that vote until the Russian proposal Monday provided a diplomatic opening. 
 
 In a speech to the nation Tuesday night, Obama made moral and strategic arguments for taking action on Syria, challenging Congress and the American public to look at video footage of victims of the chemical attack. 
 
 Russian President Vladimir Putin responded with an op-ed posted Wednesday night on the New York Times' website, saying "there is every reason to believe" Syrian troops weren't responsible, while challenging Washington and the idea of "American exceptionalism." 
 
 His remarks provoked a strong reaction in the United States, with some U.S. politicians deeming them insulting and sickening. But rather than step back, Putin spokesman Dmitry Peskov fired back by claiming Washington was "unaccustomed (to) competition" in global matters and has "grown too used to patting everyone on the back patronizingly." 
 
 Other questions loom in Washington. 
 
 One has to do with the Syrian opposition, some of whom are already receiving U.S.-funded weapons and ammunition, according to a U.S. official. Yet there's some questions about the mix of moderates and Islamist extremists among the rebels, including some who are affiliated with al Qaeda. 
 
 Then there's the issue of Syria's chemical weapons themselves, and whether it's possible to track all of them down. 
 
 Some U.S. intelligence analysts believe it's known where most of Syria's stockpile is stored, according to two U.S. officials familiar with internal discussions. But others say the United States might not be able to verify the location of up to 50% of them.
– Last week, as the US prepared for military strikes, an elite Syrian military unit once again moved the Assad regime's chemical stockpiles. Unit 450, an all-Alawite squad so secretive that even high-ranking military defectors aren't aware of its existence, has been divvying up and dispersing its stockpiles for months, US and Middle Eastern officials tell the Wall Street Journal. Officials believe the regime's 1,000 metric tons of chemical agents, once concentrated in a few large stores, are now scattered to as many as 50 locations across Syria. "We know a lot less than we did six months ago about where the chemical weapons are," one US official says. And even if the US did know all the locations, attacking Unit 450 "would be a pretty tricky affair because … if you attack them you may reduce the security of their weapons," a former Defense Intelligence Agency member says. For the same reason, the US won't share the location of stockpiles with the rebels. In other Syria news: John Kerry says his first day of talks with Russian counterpart Sergei Lavrov was "constructive," the New York Times reports. The sides remain divided on whether the UN resolution should have a military component. Kerry argued for that military component forcefully in lengthy remarks yesterday. Lavrov seemed taken aback. "I'm not prepared with the extended political statement," he said. "Diplomacy likes silence." One thing has already come out of the talks: The sides agreed to hold peace talks later this month in New York in the hopes of ending the war diplomatically, CNN reports. Bashar al-Assad, meanwhile, is feeling emboldened enough to make demands. Yesterday he said he'd only relinquish his chemical weapons if the US "ceases arms deliveries to terrorists," meaning the rebels. Assad also suggested that the Russian plan could be used to drag things out. "It doesn't mean that Syria will sign the documents, fulfill the obligations, and that's it," he said.