Update 11:00 p.m.: Based on multiple media reports, all citing unnamed officials, the Obama administration has decided to start supplying some Syrian rebel groups with arms and ammunition. As we've outlined below, the Wall Street Journal was the first to report that the White House had made a decision on this — they still haven't officially confirmed — and that report has been matched by both the Associated Press and the New York Times. The CIA is responsible for coordinating the supplies, according to all the reports. The Times says that the arms will be limited to "small arms and ammunition," for now. 

Original post: The U.S. said on Thursday that the Syrian government used chemical weapons on rebels, and the military is working on a proposal to arm the rebels and set up a no-fly zone along the border with Jordan.

Deputy national security adviser Ben Rhodes said in a conference call with reporters that the U.S. had made a "high confidence assessment that chemical weapons have been used on a small scale by the Assad regime," over the last year, including the nerve gas sarin in small amounts. Rhodes said there was "no reliable, corroborated reporting to indicate that the opposition in Syria has acquired or used chemical weapons." According to an internal memo, The New York Times reports, intelligence agencies believe between 100 and 150 people have died from chemical attacks. More than 93,000 have died in the two-year conflict. President Obama "said chemical weapons would change his calculus," Rhodes said, "and it has." According to The Wall Street Journal, Obama has authorized arming moderate Syrian rebels.

The potential no-fly zone would stretch up to 25 miles into Syria, the Journal's Julian E. Barnes and Adam Entous report, and would be enforced with aircraft flown from bases in Jordan. But Rhodes stressed that a decision to take military action had not yet been made -- because the costs would be high, and require a longer-term commitment. So why help the rebels now? "There has been an urgency to the situation for two years," Rhodes said, but the use of chemical weapons violates international norms, and recently "we have seen Hezbollah and Iran increase their involvement in the conflict that has caused an influx of additional fighters to the conflict." Rhodes said aid to the opposition would be "different in scope and scale... than what we provided before." But the Journal says the White House would not comment on its report that the ban on arming rebels had been lifted. That report is apparently based sources who referred to a "classified order to authorize the Central Intelligence Agency to provide arms to the rebels." The Associated Press, citing "three U.S. officials," also reported that Obama decided to lift the ban on lethal aid, adding, "The officials cautioned that no decisions had been made on the specific type of weaponry or when it would reach the Syrian rebels." 

Sen. John McCain welcomed the news on the Senate floor, saying, "We must change the battlefield equation." McCain got ahead of the White House, saying the U.S. would arm Syrian rebels. "We will be assisting the Syrian rebels in Syria by providing them with weapons and other assistance," McCain said. "I applaud the president." Then McCain took it back, saying Obama had not yet decided to arm the rebels. McCain and Sen. Lindsey Graham later released a statement saying they applauded Obama changing policy toward Syria, but "Now is not the time to merely take the next incremental step." The Journal's report indicates McCain was right the first time. But there is some ambiguity in the language here that still isn't resolved. Later on Thursday, McCain told CNN that he'd based his floor statement on knowledge that Obama was to provide "military assistance" to the rebels. That would match the White House's more ambiguous promise of "military support," which doesn't necessarily mean arming the rebels. But the language of a senior U.S. official, quoted by the Journal, is much clearer: "The red line has been crossed and now we are going to go ahead with arming the opposition." 

The news has seemingly swayed at least one lawmaker to join in the calls for an intervention in Syria: House Foreign Affairs Committee Chair Rep. Ed Royce, as Foreign Policy reports, used to be against the U.S. arming the rebels. But here's his statement from Thursday afternoon: 

"It is now clear that the Assad regime has crossed a red line... I support the President's decision to expand assistance for the vetted Syrian opposition, and I encourage the Administration to begin, in earnest, arming the Free Syrian Army." 

President Obama said on August 20 that his "red line" was if the Syrian government used chemical weapons on its people. In March, Obama said chemical weapons would be a "game changer" but it wasn't clear the government had used them, or that the line had been scripted. But Obama did not take action, drawing criticism from many hawkish lawmakers, and, on Wednesday, former President Bill Clinton. The evidence Syrian used chemical weapons has slowly mounted. In April, Wired reported that American intelligence officials had found some Syrians' blood tested positive for sarin. Syrian soil samples tested positive for chemical weapons, British scientists found. The European Union found the Syrian government used chemical weapons this week. A Syrian refugee camp in Jordan is now that country's fifth-largest city.

Meanwhile, the White House said that they've provided briefs their findings on chemical weapons to Russia, one of Syria's few allies, ahead of next week's G8 summit. The U.N also received similar information. Syrian opposition groups have already called for the U.S. to provide sophisticated weaponry, including anti-aircraft weapons, to the rebels, Reuters reports.