Until August loan caluclator The nerve agent sarin was among the weapons used by Assad's government, and an estimated 100 to 150 people have been killed by chemical weapons. President Barack Obama had previously stated that the verified use of chemical weapons was a "red line" for more involvement in the conflict, but the United States has hesitated to offer more tangible support. The administration is wary of becoming entangled in yet another overseas war similar to Afghanistan and Iraq.