More than half of Senate Republicans are demanding a classified briefing next week from the administration on its plan to counter Iran, in response to the administration’s recent decision to waive sanctions on the Islamic republic to allow Iraq to continue to purchase electricity from Tehran.

The waiver is believed to allow Iran to access an additional $10 billion in funds, which the administration says are subject to a vetting process to limit them to humanitarian purposes. The waiver has been renewed regularly under multiple administrations, arguing that Iraq has no alternative source for electricity and that cutting off Iranian electricity would destabilize the U.S. partner.

“Money is fungible,” a letter to top administration officials, led by Sen. Tim Scott (R-SC), reads. “Combined with the $10 billion waiver extension, the administration has provided Iran with access to roughly $16 billion in assets over the past four months; assets that can be used — now or in the future — to offset the cost of the Iranian regime’s increase in destabilizing activities across the region.”

The signatories argue that the administration’s “military and economic responses to Iran and its proxies have not only been disproportionate, they appear to be completely disjointed.”

They asked the administration to provide a classified briefing by Dec. 7 on its strategy to deter Iran and prevent escalation in the Middle East, including “an estimation of how Iran has already leveraged — and could in the future leverage — against U.S. persons and interests the tens of billions in assets it now has access to due to your administration’s use of U.S. sanctions waivers.”

Signatories to the letter include Sens. Roger Wicker (R-MS), Chuck Grassley (R-IA), Mike Crapo (R-ID), Thom Tillis (R-NC), Kevin Cramer (R-ND), Mike Braun (R-IN), Ted Budd (R-NC), J.D. Vance (R-OH), Bill Cassidy (R-LA), Pete Ricketts (R-NE), Shelley Moore Capito (R-WV), John Cornyn (R-TX), Cynthia Lummis (R-WY), Bill Hagerty (R-TN), Marco Rubio (R-FL), John Hoeven (R-ND), Roger Marshall (R-KS), Steve Daines (R-MT), Ted Cruz (R-TX), Tom Cotton (R-AR), John Barrasso (R-WY), Katie Britt (R-AL), Joni Ernst (R-IA) and Deb Fischer (R-NE).

Also on Thursday, the House passed a bill that would freeze the $10 billion and any other attempts by the administration to lift sanctions on Iran.

The letter follows weeks of outcry from congressional Republicans over the extended sanctions waiver.