US President Barack Obama has said the Syrian President Bashar al-Assad would be held accountable if chemical weapons had been used in his country.
Obama, on a visit to Israel, said the US was still investigating whether the weapons had been used.
Speaking at a joint news conference in Jerusalem with Israeli Prime Minister Benjamin Netanyahu, he said: "We have been clear that the use of chemical weapons against the Syrian people would be a serious and tragic mistake.
"The Assad regime must understand that they will be held accountable for the use of chemical weapons or their transfer to terrorists."
President Barack Obama set aside Middle East politics today to marvel at the beauty of the ancient archaeological city of Petra.
For all the warm words from the Barack Obama during his trip to Israel this week, an Israeli apology might have the most lasting impact.
President Obama appealed to young Israelis to pursue the path of peace with the Palestinians, during his visit to Israel.