US to aid Syrian rebels after concluding regime has used chemical weapons

US and European intelligence analysts believe Bashar al-Assad's regime has used chemical weapons against its own people, according to a memo circulated within the US government on Thursday.

The New York Times first cited unnamed American officials as saying they believe President Barack Obama now has the proof he has sought of chemical weapons being used in the Syrian conflict. That proof has been a sticking point in deciding both whether the president's "red line" for intervention has been crossed and the shape US intervention should take.

The White House confirmed Thursday evening that it will be militarily aiding the Syrian rebels in response to convincing evidence of chemical weapons use by the regime.

"Put simply, the Assad regime should know that its actions have led us to increase the scope and scale of assistance that we provide to the opposition, including direct support to the [Supreme Military Council]. These efforts will increase going forward," the adminstration said in a statement.

In spite of the revelation, what continued intervention might entail is still an open question. Soon after the news of the assessment broke on Thursday, the Wall Street Journal reported that a US military proposal for arming the rebels in Syria includes plans for a no-fly zone. That zone would extend "up to 25 miles into Syria [and] would be enforced using aircraft flown from Jordanian bases and flying inside the kingdom," the Journal wrote.

Deputy National Security Advisor for Strategic Communications Ben Rhodes told NBC News on Thursday that small-scale chemical weapons use by the Syrian regime is estimated to have killed at least 100 people. "However, casualty data is likely incomplete," Rhodes added.