Obama still opposes putting American troops on the ground in Syria and the U.S. has made no decision on operating a no-fly zone over Syria, Rhodes said.
U.S. officials said the administration could provide the rebels with a range of weapons, including small arms, ammunition, assault rifles and a variety of anti-tank weaponry such as shoulder-fired remote-propelled grenades and other missiles. However, a final decision on the inventory has not been made, the officials said.
Most of those would be weapons the opposition forces could easily use and not require much additional training to operate. Obama's opposition to deploying American troops to Syria makes it difficult to provide much large-scale training. Other smaller- scale training can be done outside Syria's borders.
A U.S. official said the CIA and special operations trainers have already been training Syrian rebels on the use of anti-aircraft weaponry provided by the Persian Gulf states, as well as encrypted communications equipment, and was expected to run the expanded training program as well.
All of the officials insisted on anonymity in order to discuss internal administration discussions.
Word of the stepped up assistance followed new U.S. intelligence assessments showing that Assad has used chemical weapons, including sarin, on a small scale multiple times in the last year.
U.S. intelligence estimates 100 to 150 people have been killed in those attacks, the White House said, constituting a small percentage of the 93,000 people killed in Syria over the last two years.
The White House said it believes Assad's regime still maintains control of Syria's chemical weapons stockpiles and does not see any evidence that rebel forces have launched attacks using the deadly agents.
The Obama administration announced in April that it had "varying degrees of confidence" that sarin had been used in Syria. But they said at the time that they had not been able to determine who was responsible for deploying the gas.