Syrian rebels sit on their armored vehicle as they patrol at Khaldiyeh neighborhood, in Homs province, central Syria. AP/Fadi Zaidan
The newspaper reported on its website that the US State Department has sent separate shipments of vehicles and other materials, including new types of non-lethal gear, sophisticated communications equipment and advanced combat medical kits.
The CIA, contacted by AFP late on Wednesday, said it had no comment on the Washington Post report.
The arms shipments – which the daily said are limited to light weapons and other munitions that can be tracked – arrive at a crucial moment in the bloody standoff between the rebels and the Damascus government.
Read: US military interventions are 'alarming', says Putin
The Post cited US officials who said the goal of the non-lethal assistance is to help foster cohesion among units of Syria's disjointed armed opposition.
Forces loyal to President Bashar al-Assad carried a flag on Wednesday after taking the town of Qusayr. (Reuters Photo)
US President Barack Obama on Tuesday agreed to give international diplomacy a chance to resolve the conflict before unleashing military strikes.
Read: US puts strike on hold, gives diplomacy time on Syria
The long-awaited military aid comes one day after the US president told the American people in a nationally broadcast address that he was deferring taking military action in Syria in order to study a Russian initiative which would see Damascus relinquish its chemical weapons.
He made his appeal to US lawmakers after a weeks long build up to war in which he sought congressional approval for military strikes against Syria for using chemical weapons on its own people.
Demonstrators protest at the White House in Washington against a possible US attack on Syria. (AFP Photo)
Obama made his threats of strikes in response to the August 21 attack, when Syrian forces allegedly killed 1,400 people in rebel-held areas near Damascus using sarin gas, according to US estimates.
Read: Full text of President Obama's speech on Syria
But the US leader in his speech late on Tuesday gave assurances that there would be no military force for the moment, given the Russian plan.
"This initiative has the potential to remove the threat of chemical weapons without the use of force, particularly because Russia is one of Assad's strongest allies."