Preparations for the alternative system are “at an advanced stage” according to Maja Kocijancic, spokeswoman for EU foreign policy chief Federica Mogherini. “I hope that we can announce the launch very soon,” she told reporters last week in Brussels.

A senior administration official, who spoke on condition of anonymity, said on Friday that the US will fully enforce its sanctions and hold individuals and entities accountable for undermining them.

“The choice is whether to do business with Iran or the United States,” Sen. Tom Cotton, R-Ark., told the AP. “I hope our European allies choose wisely.”

Trump called the Iran nuclear agreement a “horrible, one-sided deal.” He pulled out of the pact last year and restored US sanctions on Iran. Tehran continues to abide by the agreement, and the remaining nations in the pact are working hard to keep it intact.

The Trump administration’s “maximum pressure campaign” is meant to force Iran to radically alter their policies on developing ballistic missiles, supporting regional militant groups, and violating human rights.

As well, the US worries that an alternative money payment system could become successful enough to compete with the international bank transfer system known as SWIFT, and eventually supplant SWIFT as the leading global institution for financial institutions to send and receive information about banking transactions.

The Europeans claim that the alternative money transfer system would be used only for humanitarian transactions, but the US is suspicious. Sen. Marco Rubio, R-Fla., told the AP, “We should oppose efforts to create foreign financial channels that Iran could use to circumvent America’s maximum pressure campaign against it, especially when humanitarian exceptions are already in US sanctions laws.”

Meanwhile, the US is preparing to co-host a conference with Poland next month that will focus on combatting Iranian threats. Iranian Foreign Ministry Spokesman Bahram Qassemi called the Warsaw Summit, “an American move with clear goals. It is not necessarily about Iran, but pursues specific goals… I think one of the major goals of this conference is to create division among European countries.” The EU is still deciding on whether or not to take part in this conference.