US officials say they see Iran's hand in the increasingly brutal crackdown on opposition strongholds in Syria, including evidence of Iranian military and intelligence support for government troops accused of mass executions and other atrocities in the past week.
Three US officials with access to intelligence reports from the region described a spike in Iran­ian-supplied arms and other aid for Syrian leader Bashar al-Assad at a time when the regime is mounting an unprecedented offensive to crush resistance in the key city of Homs.
"The aid from Iran is increasing, and is increasingly focused on lethal assistance," said one of the officials, insisting on anonymity to discuss intelligence reports from the region.
The expanded Iranian role in the conflict has been underscored by reports - supported by U.S. intelligence findings - that an Iranian operative was recently wounded while working with Syrian security forces inside the country.
The flow of military aid to Assad comes as Arab states are considering arming the regime's opponents, raising the risk of a wider conflict that US fears could spread to neighboring countries.
In addition, the reports about Iranian support for Syria come as US officials are seeking to rally international support for efforts to drive Assad from power without resorting to arming the rebels. Iran has made no secret of its support for the Assad regime, though President Ahmadinejad has made repeated calls for a peaceful solution.