The United States is boosting military support to the main Syrian rebel group after determining that the government has used chemical weapons against the opposition, a top White House official said on Thursday (June 13).

"The president has made a decision about providing more support to the opposition, that will involve providing direct support to the (Supreme Military Council), that includes military support," Deputy National Security Advisor Ben Rhodes told reporters on a conference call. "This is going to be different in both scope and scale in terms of what we are providing to the SMC than what we have provided before."

The Supreme Military Council is the military wing of the main civilian opposition group.

Rhodes said that its intelligence community has determined the government of Syrian President Bashar al-Assad used chemcial weapons "on a small scale against the opposition multiple times in the last year."

He said that 100 to 150 deaths are attributed to that chemical weapons use, but added that is it probable there is a greater number of unaccounted casualties.

Presented by Adam Justice