BEIRUT — The U.N. experts investigating last week’s alleged chemical weapons strike outside Damascus left Syria and crossed into neighboring Lebanon early Saturday, departing hours after President Barack Obama said he is weighing “limited and narrow” action against a Syrian regime that the administration has accused of launching the deadly attack.


An Associated Press crew saw the U.N. personnel enter Lebanon from Syria through the Masnaa border crossing and then drive in a 13-car convoy to the Beirut airport. After four days of on-site inspections, the team wrapped up its investigation Friday into the suspected chemical attack on rebel-held suburbs of Damascus on Aug. 21.


The experts take with them blood and urine samples from victims as well as soil samples from the affected areas for examination in laboratories in Europe. The United Nations has said it will try to expedite its final report, and U.N. disarmament chief Angela Kane is to brief Secretary-General Ban Ki-moon later Saturday on the investigation.


With the inspectors now out of Syria, the looming confrontation between the U.S. and President Bashar Assad’s regime moves one step closer to coming to a head. Most observers viewed U.S. military action as unlikely while the U.N. team was still on the ground inside Syria, but the American administration has made clear that it is confident in its assessment and could act before the United Nations releases the results of its probe.


Obama has said that if he opts for a military strike, any operation would be limited in scope and only aimed at punishing Assad for his alleged use of chemical weapons.


But U.S. action carries the potential to trigger retaliation by the Syrian regime or its proxies against U.S. allies in the region, such as Jordan, Turkey and Israel. That would inject a dangerous new dynamic into a Syrian civil war that has already killed more than 100,000 people, forced nearly 2 million to flee the country and inflamed sectarian tensions across the Middle East.


While Obama has long been wary of U.S. military involvement in the conflict, the administration on Friday forcefully made its case for action against Syria in the wake of last week’s events outside Damascus. It accused the Assad regime of carrying out what it says was a chemical attack on Aug. 21 that killed at least 1,429 people – far more than previous estimates – including more than 400 children.


With France as his only major public ally, Obama told reporters he has a strong preference for multilateral action.


“Frankly, part of the challenge we end up with here is a lot of people think something should be done but nobody wants to do it,” he said.


The U.S. already has warships in place in the eastern Mediterranean Sea near Syria’s coastal waters. The vessels are armed with cruise missiles, long a first-line weapon of choice for presidents because they can strike distant targets without need of air cover or troops on the ground.


The Syrian government dismissed the administration’s claims as “flagrant lies” akin to faulty Bush administration assertions before the Iraq invasion that Saddam Hussein had weapons of mass destruction. A Foreign Ministry statement read on state TV late Friday said that “under the pretext of protecting the Syrian people, they are making a case for an aggression that will kill hundreds of innocent Syrian civilians.”


In Damascus, residents braced themselves in anticipation of strikes.


“We are anticipating it starting tonight, since the inspectors have left, but we don’t really know,” said Nour, who lives on the outskirts of Damascus.


“Just in case, we stocked up on some water and food. Our building has a basement that we can use as a shelter. The building supervisor started preparing it a couple of days ago, he cleaned it and we put some pillows, blankets, water and a first aid kit with basic medications,” she added. She gave only her first name for security reasons.


Syrian state TV on Saturday morning broadcast footage of Syrian soldiers training, fighter jets soaring in the sky and tanks firing at unseen targets, all to the backdrop of martial music. The station’s morning talk shows were dominated by discussions about a potential U.S. military strike.


Obama met with his national security aides at the White House on Friday and then with diplomats from Baltic countries, saying he has not yet made a final decision on punitive strikes.


But the administration did nothing to discourage the predictions that action was imminent. That impression was heightened both by sharply worded remarks from Secretary of State John Kerry and the release of an unclassified intelligence assessment that cited “high confidence” that the Syrian government carried out the attack.


In addition to the dead, the assessment reported that about 3,600 patients “displaying symptoms consistent with nerve agent exposure” were seen at Damascus-area hospitals after the attack.


In his remarks, Kerry added that “a senior regime official who knew about the attack confirmed that chemical weapons were used by the regime, reviewed the impact and actually was afraid they would be discovered.”


The assessment did not explain its unexpectedly large count of 1,429 deaths, far in excess of an estimate from Doctors Without Borders from earlier this week that put the toll at 355. Not surprisingly – given the nature of the disclosure – it also did not say expressly how the United States knew what one Syrian official had allegedly said to another.


Mindful of public opinion, Kerry urged Americans to read the four-page assessment for themselves. He referred to Iraq – when Bush administration assurances that weapons of mass destruction were present proved false, and a U.S. invasion led to a long, deadly war. Kerry said this time it will be different, and that “we will not repeat that moment.”


Citing an imperative to act, the secretary of state said “it is directly related to our credibility and whether countries still believe the United States when it says something. They are watching to see if Syria can get away with it because then maybe they, too, can put the world at greater risk.”


While Obama was having trouble enlisting foreign support, French President Francois Hollande was an exception. The two men spoke by phone, then Hollande issued a statement saying they had “agreed that the international community cannot tolerate the use of chemical weapons, that it must hold the Syrian regime responsible and send a strong message to denounce the use of (such) arms.”


Obama has long been wary of U.S. military involvement in Syria’s civil war, as he has been with tumultuous events elsewhere during the so-called Arab Spring. In the case of Syria, his reluctance stems in part from recognition that while Assad has ties to Iran and the Lebanese militant group Hezbollah, the rebels seeking to topple him have connections with al-Qaida-linked groups.


Still, Obama declared more than a year ago that the use of chemical weapons would amount to a “red line” that Assad should not cross. And Obama approved the shipment of small weapons and ammunition to the Syrian rebels after an earlier reported chemical weapons attack, although there is no sign the equipment has arrived.


___


Associated Press writer Yasmine Saker contributed to this report.


Related on HuffPost:






  • Syrian refugee, Ahmed al Delly, 59, from Daraa in Syria, reacts as he speaks about his wife, four sons, and two daughters, who are still in Daraa but he has had no contact with them, after the prayer of Eid al-Fitr, that marks the end of the holy fasting month of Ramadan, at Zaatari Syrian refugee camp, in Mafraq, Jordan, Thursday, Aug. 8, 2013. (AP photo/Mohammad Hannon)





  • This image provided by Shaam News Network on Thursday, Aug. 22, 2013, which has been authenticated based on its contents and other AP reporting, purports to show mourners next to bodies of victims of an attack on Ghouta, Syria on Wednesday, Aug. 21, 2013. (AP Photo/Shaam News Network)





  • This image provided by by Shaam News Network on Thursday, Aug. 22, 2013, which has been authenticated based on its contents and other AP reporting, purports to show several bodies being buried in a suburb of Damascus, Syria during a funeral on Wednesday, Aug. 21, 2013. (AP Photo/Shaam News Network)





  • Columns of smoke rising from heavy shelling in the Jobar neighborhood in west Damascus, in Cairo, Syria, Thursday, Aug. 22, 2013. (AP Photo/Hassan Ammar)





  • In this citizen journalism image provided by the Media Office Of Douma City, which has been authenticated based on its contents and other AP reporting, a Syrian man mourns over a dead body after an alleged poisonous gas attack fired by regime forces, according to activists, in Douma town, Damascus, Syria on Wednesday, Aug. 21, 2013. (AP Photo/Media Office Of Douma City)





  • Syrian refugees cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013. (AP Photo/Hadi Mizban)





  • This citizen journalism image provided by the Local Committee of Arbeen which has been authenticated based on its contents and other AP reporting, shows a Syrian man reacts as he carries a dead body of a Syrian girl, after an alleged poisonous gas attack fired by regime forces, according to activists in Arbeen town, Damascus, Syria, Wednesday, Aug. 21, 2013. (AP Photo/Local Committee of Arbeen)





  • This citizen journalism image provided by the Local Committee of Arbeen which has been authenticated based on its contents and other AP reporting, shows Syrian citizens trying to identify dead bodies, after an alleged poisonous gas attack fired by regime forces, according to activists in Arbeen town, Damascus, Syria, Wednesday, Aug. 21, 2013. (AP Photo/Local Committee of Arbeen)





  • This citizen journalism image provided by the Local Committee of Arbeen which has been authenticated based on its contents and other AP reporting, shows dead bodies of Syrian citizens in Arbeen town, Damascus, Syria, Wednesday, Aug. 21, 2013. (AP Photo/Local Committee of Arbeen)





  • A Syrian family sits in a tent at Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Iraq, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • Syrian refugees stand in a queue to receive free food at Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • Syrian refugees wait to receive a tent at Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Iraq, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • Syrian refugees wait to receive a tent at Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Iraq, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • Syrian refugees gather for food aid at Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Iraq, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • Syrian refugees wait for food aid at Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Iraq, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • A Syrian military soldier holds his AK-47 with a sticker of Syrian President Bashar Assad as he stands guard at a check point on Baghdad street, in Damascus, Syria, Wednesday, Aug. 21, 2013. (AP Photo/Hassan Ammar)





  • A Syrian military soldier holds his AK-47 with a sticker of Syrian President Bashar Assad and Arabic that reads, “Syria is fine,” as he stands guard at a check point on Baghdad street, in Damascus, Syria, Wednesday, Aug. 21, 2013. (AP Photo/Hassan Ammar)





  • This citizen journalism image provided by the Local Committee of Arbeen which has been authenticated based on its contents and other AP reporting, shows a Syrian man receiving treatment, in Arbeen town, Damascus, Syria, Wednesday, Aug. 21, 2013. (AP Photo/Local Committee of Arbeen)





  • Syrian refugees cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013. (AP Photo/Hadi Mizban)





  • Syrian refugees cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013. (AP Photo/Hadi Mizban)





  • A general view of the Kawergost refugee camp in Irbil, 217 miles (350 kilometers) north of Baghdad, Iraq, Wednesday, Aug. 21, 2013. (AP Photo/Hadi Mizban)





  • In this image taken from video posted by Ugarit News, which has been authenticated based on its contents and other AP reporting, purports to show a fireball from an explosion at a weapons depot set off by rocket attacks that struck government-held districts in the central Syrian city of Homs on Thursday, Aug. 1, 2013. (AP Photo/Ugarit News via AP video)





  • Syrian refugees gather for food aid after cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013. (AP Photo/Hadi Mizban)





  • In this image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, a Syrian man comforts a child injured by a missile strike in Raqqa, Syria, Wednesday, Aug. 7, 2013. (AP Photo/Shaam News Network via AP video)





  • Syrian refugees cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013. (AP Photo/Hadi Mizban)





  • In this citizen journalism Monday, Aug. 12, 2013, image provided by Aleppo Media Center AMC, which has been authenticated based on its contents and other AP reporting, buildings are seen damaged from the shelling of Syrian forces at Karm al-Jabal area in Aleppo province, Syria. (AP Photo/Aleppo Media Center, AMC)





  • In this citizen journalism Monday, Aug. 12, 2013, image provided by Aleppo Media Center AMC, which has been authenticated based on its contents and other AP reporting, Syrian rebels open fire as they battle against the Syrian forces in Aleppo, Syria. (AP Photo/Aleppo Media Center, AMC)





  • In this image released by the Syrian official news agency SANA, a Syrian army soldier stands behind his machine gun during a battle against the Syrian rebels at an unidentified location in Latakia province, Syria, Tuesday, Aug. 13, 2013. (AP Photo/SANA)





  • In this image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, a Syrian man carries an injured child away from a missile strike in Raqqa, Syria, Wednesday, Aug. 7, 2013. (AP Photo/Shaam News Network via AP video)





  • In this image released by the Syrian official news agency SANA, a Syrian forces tank fires during a battle against the Syrian rebels at an unidentified location in Latakia province, Syria, Tuesday, Aug. 13, 2013. (AP Photo/SANA)





  • In this image taken from Sunday, Aug. 11, 2013, video obtained from the Sham News Network, which has been authenticated based on its contents and other AP reporting, a rebel fighter fires a gun in a valley in an unidentified location in Latakia province, Syria. (AP Photo/Sham News Network via AP video)





  • Mansour Mahameed, 26, from Daraa city in Syria, a former Free Syrian Army fighter who lost his leg last March after the Syrian troops bombing, prepares to sit for the Eid al-Fitr prayer that marks the end of the holy fasting month of Ramadan at Zaatari Syrian refugee camp in Mafraq, Jordan, Thursday, Aug. 8, 2013. (AP Photo/Mohammad Hannon)





  • Syrian refugees cross into Iraq at the Peshkhabour border point in Dahuk, 260 miles (430 kilometers) northwest of Baghdad, Iraq, Tuesday, Aug. 20, 2013. (AP Photo/Hadi Mizban)





  • In this image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, a Syrian man carries an injured child away from a missile strike in Raqqa, Syria, Wednesday, Aug. 7, 2013. (AP Photo/Shaam News Network via AP video)





  • In this photo released by the Syrian official news agency SANA, dead bodies of Syrian rebels are seen on the ground, killed during ambush by Syrian forces near the Damascus suburb of Adra, Syria, Wednesday Aug. 7, 2013. (AP Photo/SANA)





  • In this image taken from video posted by Shaam News Network, which has been authenticated based on its contents and other AP reporting, purports to show a fireball from an explosion at a weapons depot set off by rocket attacks that struck government-held districts in the central Syrian city of Homs on Thursday, Aug. 1, 2013. (AP Photo/Shaam News Network via AP video)





  • This image posted on the official Facebook page of the Syrian Presidency on Thursday, Aug. 1, 2013 purports to show Syrian President Bashar Assad shaking hands with a soldier during Syrian Arab Army day in Darya, Syria. (AP Photo/Syrian Presidency via Facebook)





  • This image posted on the official Facebook page of the Syrian Presidency on Thursday, Aug. 1, 2013 purports to show Syrian President Bashar Assad walking with soldiers with during Syrian Arab Army day in Darya, Syria. (AP Photo/Syrian Presidency via Facebook)





  • In this image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, a Syrian youths run away from the scene of a missile strike in Raqqa, Syria, Wednesday, Aug. 7, 2013. (AP Photo/Shaam News Network via AP video)