The US took an odd and winding path from denial to acceptance of “evidence” of Syria’s use of chemical weapons, but the putative proof behind the allegations is flimsy, at best.
The “publicly available” evidence, none of which is particularly new, falls well short of the standards a UN team would need for “proof” of the use of chemical weapons during the civil war. Though there has been some hinting at other, secret evidence Israeli military officials, who are the source of the allegations, are pointing entirely to rebel-provided photographs as building their case.
The Syrian government has denied using chemical weapons, and officials continue to insist they believe they can win the civil war without them. Though both rebels and government forces have repeatedly claimed they are on the brink of winning the war, it seems stalemated and nowhere near so dire that Syria would’ve been forced to play the chemical weapons card.
The UN has been trying to deploy a team to investigate the allegations in Syria, with the Assad government the first to urge them to come. The visit has been delayed, however, with the UN team demanding not only access to the alleged site of usage, but virtually the entire nation.