US President Donald Trump on Thursday emphasized “tremendous” economic consequences for countries that keep on doing business or giving money to Iran or in its favor, launching what he called an unprecedented economic pressure campaign against Tehran.

On the Truth Social, social media platform, Trump declared the scheme to be the “most crushing economic operation ever taken against any country” and declared it would be economic warfare and isolation “on an unprecedented scale.”

Any nation that offers a “form of an economic lifeline” to Iran would have “severe consequences”, Trump said. He said there must be an instant termination of activities such as oil smuggling, swap lines and cash transfers, the establishment of exchange houses, ship registries and front companies.

The US President didn’t specify a nation, or detail penalties, but announced that the countries at stake “knows who they are.” Prior to the present conflict started in February, Iran’s key trading partners included China, India, Turkey, Germany, South Korea and Japan.

Trump claims Iran had a “big opportunity” to strike a deal with the U.S. but chose to miss out. The new steps were an “Economic D-Day”, he called, and urged Washington’s allies to help distance Iran from the West.

He also restated this demand that Iran should not have the opportunity to obtain a nuclear weapon, and demanded that Iran is threatening regional and global security.

It is also as tensions between Washington and Tehran are running high, and the Middle East conflict has now entered its sixth month.

The US Treasury has already been running a comprehensive sanctions regime dubbed “Operation Economic Fury” to limit Tehran’s ability to access financial sources and to blow up the sources of financial revenues for Iran.