A bipartisan group of senators seeking to block US weapons sales to Saudi Arabia’s war in Yemen are trying to disarm critics by arguing that their effort won’t benefit Iran.

The four lawmakers and their allies in the human rights community insist that the Saudi-led campaign is a civil war, not a proxy war. The Senate is expected to vote on their measure to block a proposed $1.15 billion sale of tanks and other weapons on Sept. 21.

“We’ve got to do a better job of educating members that this is not a simple proxy war” between Riyadh and Tehran, resolution sponsor Chris Murphy, D-Conn., said in a conference call with reporters Monday morning. While there are “connections” between the Houthis and Tehran, he said, “It certainly doesn’t resemble a command-and-control relationship like some would have you believe.”

“But even for those members who think this is a proxy war, we need to force them to ask a question as to what our priority in the region should be,” Murphy added. “Is our priority to back Saudi [Arabia] in every single perceived proxy war with the Iranians? Or is our priority to defeat extremism, including al-Qaeda and [the Islamic State]?”