A year ago President Barack Obama gave a speech saying that if the Assad regime used chemical weapons, that would cross a red line and change his calculations.
Has that red line now been crossed?
The simple answer is that we don't yet know.
While a White House spokesman, Josh Earnest, has said the US is "appalled" by "horrifying" reports from Syria, it doesn't seem Mr Obama is inclined to pronounce.
Mr Earnest called on the Assad government to co-operate with the UN inspectors in full.
But asked if reporters would hear from the president while he is on a bus tour about lowering the cost of higher education, he said, "as we're weighing these domestic policy decisions, and as we're weighing these foreign policy decisions, the president puts the interest of the United States of America first.