Obama has resisted arming the rebels until now, a cautious approach that underscores the deep divisions within his administration. The proponents of more aggressive action, including Secretary of State John Kerry, appeared to have won out over those wary of sending weapons and ammunition into the war zone.
The U.S. has made no decision on operating a no-fly zone over Syria, Rhodes said.
The U.S. has so far provided the Syrian rebel army with rations and medical supplies. The administration has also agreed in principle to provide body armor and other equipment such as night-vision goggles to the rebels, although the Pentagon has said there has been no movement on that as yet.
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, killing an estimated 100 to 150 people.
Obama advisers believe 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 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.
The more conclusive findings announced Thursday were aided by evidence sent to the United States by France, which, along with Britain, has announced it had determined that Assad's government had used chemical weapons.
In Brussels, NATO Secretary-General Anders Fogh Rasmussen said Friday, "The international community has made clear that any use of chemical weapons is completely unacceptable and a clear breach of international law."
He said he welcomes the "clear U.S. statement" and called on Syria to "grant access to the United Nations to investigate all reports of chemical weapons use."