With the next phase of painful Iran sanctions almost here, European leaders are trying to gut them — and Treasury Secretary Steve Mnuchin is taking their side. Will President Trump let Mr. Mnuchin make him look weak, or stick with sanctions hawks like National Security Adviser John Bolton?

At issue is Iranian banks’ access to a key financial-messaging system called the Society for Worldwide Interbank Financial Telecommunication. The hawks argue that denying access to the Belgium-based SWIFT is critical to limiting Iran’s participation in the global financial system.

On November 4, when America imposes new sanctions on Iran targeting its oil exports and banks, the question is whether to include a ban on its access to SWIFT. Such sanctions could strangle Iran’s energy sector, its economic backbone, and perhaps bring its already ailing economy to a screeching halt. That, in turn, might lead to a better deal than the one President Obama & Co. secured concerning Tehran’s nuclear program.

Alas, oil can be sold clandestinely, so Iran can bypass sanctions — if it can manage to complete its sales. SWIFT, which facilitates reliable, safe and, well, swift transactions, is key to that.

Yet Team Trump is seriously considering exempting SWIFT from the sanctions. The Treasury Department, I’m told, has commissioned a CIA report that would pooh-pooh its importance. In Israel last week, Mr. Mnuchin told officials that barring Iranian banks from SWIFT is now out, reports the newspaper Israel Hayom.

“Our objective is to make sure that financial institutions do not process sanctioned transactions,” Mr. Mnuchin told the Wall Street Journal, adding, however, that some Iranian banks will keep SWIFT access.

Big mistake: For sanctions to be as effective as possible, it’s critical to completely sever Iran’s access to SWIFT. Barring Iranian banks from SWIFT, sanction hawks argue, would force it to use other transactions that are inadequate for today’s electronics-based commerce. Consider: With the sanctions in place, Turkish officials tried to help Iran skirt them using smuggled gold. (They were later convicted in Manhattan courts.)

The SWIFT service is the “zeroes and ones that help move money around” in today’s electronic-based business world, says Mark Dubowitz of the Foundation for Defense of Democracies. “Maximum pressure means cutting the Islamic Republic off from the global financial system,” he adds. Access to SWIFT is crucial for Tehran’s $400 billion economy, so denying it is a must.

As Secretary of State Hillary Clinton explained in February 2012, full denial of SWIFT is “a very effective way of further isolating Iran and the Iranian flow of financial transactions.”

Congress got President Obama to include a SWIFT ban in the sanctions imposed back then. Those sanctions were later removed as part of Team Obama’s nuclear pact, the one Mr. Trump likes to refer to as the “horrible deal.”

Treasury officials say they worry that competing global players would create their own version of SWIFT. Yet China and Russia have long threatened to weaken American power over global markets by replacing dollar-dominated banking with their own — to no avail.

Similarly, in September the European Union’s foreign policy czar, Federica Mogherini, announced a “special purpose vehicle” to facilitate Iran sanction-busting. So far, her “vehicle” is stuck in bureaucratic mud, unable to take off as European firms leave Iran in droves.

Fears of bypassing SWIFT, and weakening America’s global financial dominance, are as overstated as they were when Obama-era Treasury officials raised the exact same objections. Their fears were never realized, and they’re unlikely to materialize now.

Congress is pressuring Mr. Trump to ignore the naysayers and deny Iranian banks SWIFT access. As one senior GOP Hill staffer told me this week, “The president has to decide whether or not the administration will actually fulfill his promise of maximum pressure on Iran.”

The SWIFT fight could shape Mr. Trump’s strategy of reversing the flawed Obama nuke accord. That deal not only let Iran spend US gifts on widening its regional aggression; as evident from data Israeli spies stole (recently examined by US-based nuclear scientists) it also let Iran patiently wait a few years, and then rebuild its nuclear production lines.

It would certainly be ironic if Trump gave Iran a SWIFT exemption — since his sanctions would then be weaker than Obama’s. Is that the image the president wants in dealing with Iran?

Twitter @bennyavni. From New York Post.