The November 14th letter, signed by members of both parties after their trip to Middle East, opened with an expression of “concerns regarding Iranian presence in Syria. We recently returned from the region where we heard concerns from our close ally, about Iranian operations in Syria, particularly since the signing of a ceasefire last July, which set up de-escalation zones on …Jordan’s border.”

It added, “Iran is providing substantial amounts of support to the Syrian regime, including funds, weapons and personnel from IRGC-Quds force. Iran is estimated to have deployed about 1,300-1,800 IRGC soldiers and even some regular army Special Forces personnel to Syria.”

The 43 members of Congress warned that “should Iran be allowed to maintain a permanent military presence in Syria, it would pose a significant threat in the region, and United States interests.”

The letter showed concern about the risk of an Iranian corridor from Tehran through Iraq to Syria and into Lebanon if the strategy is not changed. “A permanent Iranian presence in Syria would connect Lebanon-based Hezbollah to Iran via Iraq and Syria. This would give Iran the ability to project power from the Persian Gulf to the Mediterranean Sea.”

One week after the US agreed with Russia on a de-escalation deal in southern Syria, the Congressmen warned that “any agreement or policy that allows Iran to station forces on or near Israel and Jordan’s border does not serve US interests.”

The letter continued, “We urge you to come to Congress with a strategy for Syria that includes how the United States plans to prevent Iran from gaining a permanent foothold in the region and to block Iranian arms exports to Hezbollah.”

“Hezbollah’s 150,000 rockets and missiles [are] larger than that of most states and could pose a grave military threat to Israel,” they wrote.

The letter came while a White House delegation visited the region to discuss concerns over the Syrian deal. A US spokeswoman at the national security council stated, We have an important, strategic, strong, collaborative relationship with the countries in the region, and US government delegations routinely visit the region to coordinate on a wide range of issues.

“While the US has made the south-west de-escalation zone a priority in its Syria policy, it has no realistic means of actually rolling back Iranian influence across the border,” said Tobias Schneider, an international security analyst based in London. He added, “Iran not only runs networks of tens of thousands of militiamen, but also [has] increased its reach in economics and politics.”