As the Trump administration prepares to reimpose hefty pre-nuclear deal sanctions on Iranian banks in November, one part of the effort—banning Iran from a key global financial messaging service—is facing resistance from Europe and some in the Treasury Department.

A research memo circulating among policymakers Thursday counters that resistance and argues that cutting off Iran from SWIFT, a service critical for facilitating cross-border financial transactions, would be essential, effective, and with precedent. The document, penned by Mark Dubowitz at the Foundation for Defense of Democracies and provided to THE WEEKLY STANDARD, is being viewed as a point-by-point response to potential ‘de-SWIFTing’ objections.

Disconnecting Iranian banks from SWIFT is essential to the U.S. sanctions regime currently being built up against Iran, the document argues. Cutting off Tehran from the service was a central part of economic pressure against the country in the run-up to the 2015 nuclear deal. Iranian banks were reconnected in 2016.

“The Islamic Republic will use whatever channels remain connected to the global financial system to continue its terror financing, money laundering, and illicit activities,” the report reads, later adding, “Economic analysis of the pre-JCPOA sanctions regime and reports from the time are conclusive that disconnecting Iran from SWIFT was a crippling step that endangered Iran’s economy.”

A range of quotes from Obama administration officials are laced throughout the document to cement this assertion. Then-Secretary of State Hillary Clinton in 2012: “We believe that using the SWIFT system is a very effective way of further isolating Iran and the Iranian flow of financial transactions.”

SWIFT cut Iran off in 2012 under the threat of congressional sanctions. The Obama administration had warned then that such penalties could hurt America’s ability to keep tabs on terror financing, the document notes, a warning now said to be repeated by opponents of barring Iran from SWIFT.

“SWIFT did not scale back cooperation; all counterterrorism cooperation with SWIFT continued. Cooperation will continue this time, too,” the memo reads. “The EU would be endangering its own citizens if it scaled back intelligence sharing.”

Some European officials are considering creating an alternative to SWIFT in case the U.S. levies sanctions, another potential side-effect of barring Iranian banks from SWIFT that the Treasury Department warned of in 2012.

“After Senators voted to pressure SWIFT, no credible alternative to SWIFT was ever established. It was not established because there is no such credible alternative,” the document says. “No legitimate bank is going to use an alternative service that is soaked in terror financing and has no access to the U.S. financial system.”

Expelling Iranian banks from SWIFT is a move with recent precedent, the memo argues. All North Korean banks were banned from SWIFT in 2017. “At the time, the banks were not subject to European Union sanctions and a European Commission spokesperson said, “This is a commercial matter for SWIFT. We do not interfere in the business decisions of any such company.””

Forcing Iranian banks out of SWIFT is “one of the most serious financial sanctions possible,” the document notes. But SWIFT itself would not necessarily be sanctioned. The 2012 legislation allows for penalties against officials on the SWIFT board of directors or on the banks represented there. “SWIFT operations would not be interrupted,” the memo says.

As of Thursday morning, the research document had begun making the rounds on Capitol Hill.

“This memo dismantles everything the Treasury Department has been telling us about why it's OK to let Iran stay connected to SWIFT,” said a senior GOP congressional staffer. “It's well within their ability to force SWIFT to disconnect the Iranians and, more importantly, it's a necessary prerequisite for implementing what the president has called for.”