Federal officials are keeping an eye on evidence of chemical weapons being used in Syria.

US Defense Secretary Chuck Hagel made the announcement Thursday.

President Obama has previously said the use of chemical weapons could trigger US reaction but Hagel was quick to say the US is still investigating.

"We need all the facts. We need all the information," said Hagel. "They are still assessing and they are still looking at what happened, who was responsible, and the other specifics that we'll need."

US officials are still trying to determine where the chemical weapons came from, how their use could affect the Syrian civil war and whether it warrants US involvement.