President Donald Trump on Wednesday issued a stern warning to any nation thinking about offering a lifeline to Iran after announcing the launch of a U.S. operation he likened to an "economic D-Day."

"Today, I am announcing the MOST CRUSHING ECONOMIC OPERATION EVER TAKEN AGAINST ANY COUNTRY! This will be Economic Warfare and Isolation on an unprecedented scale," Trump wrote on Truth Social. 

"I am also announcing that ANY country that allows its financial institutions, businesses, airports, or government entities to provide any type of lifeline to Iran will itself face TREMENDOUS Economic Consequences.

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"Oil smuggling, swap lines, cash transfers, exchange houses, ship registries, front companies — It all needs to stop NOW," he continued. "You know who you are. This will be an ECONOMIC D-DAY, and we need all of our Allies to stand with the United States of America to isolate, and defeat, the Iran threat. These maniacs are on the ropes, and these HISTORIC MEASURES will cripple them and their ability to project terror worldwide."

Trump said Iran's navy and air force are destroyed, while their production facilities have all been reduced to "rubble."

The president added Tehran's currency is "worthless," and the country as a whole "is hanging by a thread."

Wednesday's announcement came amid a pressure campaign from Washington, including a naval blockade, to get Iran to capitulate. Earlier in the week, Iranian Foreign Ministry spokesperson Esmail Baghaei accused Washington of relying on economic sanctions when diplomacy fails, calling it an "addiction," according to Yemen's state-run news agency. 

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Iranian leaders on Wednesday warned neighboring Gulf states against assisting the U.S. military. 

The United Arab Emirates (UAE), a close U.S. ally and regional power, on Wednesday severed all financial and economic ties with Iran, citing a military escalation by Tehran with incoming missile fire. Iran has attacked its neighbors in similar fashion in the months since the war began. 

Amid the war with the United States, Tehran has relied on regional groups and proxies to fight back, though the country is traditionally allied with China and Russia.  

On Monday, Trump threatened to bomb Oman if the country acts as a barrier to reopening the Strait of Hormuz, a major point of contention on both sides of the conflict. 

He said the U.S. may return to talks with Tehran "maybe at some point" and that the Strait of Hormuz is "not going to be quite as important as it was in the past" as several states explore alternative sources for oil.