U.S. intelligence agencies believe it is likely the Syrian government has used the lethal nerve agent sarin.
But President Obama says the evidence is not strong enough for the U.S. to take action.
"What we now have is evidence that chemical weapons have been used inside of Syria but we don't know how they were used, when they were used, who used them," said President Obama.
Some analysts believe using only a small amount of these weapons is designed to avoid mass casualties and is a strategic decision by Syrian President Bashar al-Assad.
Joseph Holliday is a former intelligence officer in the U.S. Army who is now a senior research analyst at the Institute for the Study of War.
“And so this careful introduction is designed to ensure that there is not a major reaction, which will allow him to ratchet up the use of the [chemical] weapons in the future," said Holliday.
The commander of the Free Syrian Army, General Salim Idris, said in a letter to President Obama that the Assad government's use of chemical weapons could be a prelude to a larger deployment of such weapons as part of that government's strategy.