McCain is a supporter of helping the rebels inside Syria and accused the White House administration of not acting regarding Syria. He questioned how good the advice was that Dempsey has been providing the White House the last two years.
McCain, a Republican from Arizona, suggested that the risk of not acting in Syria was more risky than what the U.S. would face by having a more active role supporting the rebels.
Dempsey countered McCain by saying the country has not been inactive.
The White House has said the rebels would be helped, but leaders of the rebels in Syria have said they have not yet been given the weapons promised.
Dempsey acknowledged later than there had been a shift in the tide in favor of the government forces in Syria led by President Bashar al-Assad.
He also indicated that ebbs and flows in momentum have taken place between each side during the two plus years the conflict has taken place.
The government of the U.S. has been concerned over the presence of extremists affiliated with al-Qaeda within the rebel groups in Syria, which complicates the policy of supporting those rebel groups.
Dempsey said that recent military experience for the U.S. should counsel caution, since introducing military force could make the situation worse, which was an apparent reference to the experiences of the U.S. in Iraq.