US President Donald Trump declared on Wednesday that the United States would launch an unprecedented campaign of economic warfare and isolation against Iran.

In a post on Truth Social, Trump said Iran had failed to take advantage of what he called a major opportunity to reach a deal with Washington.

"No one has given the Islamic Republic of Iran a greater opportunity to make a Deal than me. TRAGICALLY, for them, they have failed to take it," he wrote.

Trump said the new measures would target Iran's ability to maintain international economic ties and warned that countries and entities that continue providing assistance to Tehran could face consequences from Washington.

"Therefore, 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 claimed that Iran's military capabilities had already suffered major damage, saying, "Their navy is gone, their air force is destroyed, their military factories are now rubble, their currency is worthless, and their country is hanging by a thread."

He also warned governments, financial institutions and businesses around the world against providing Iran with economic support.

"Today, 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."

Trump specifically called for an end to activities including oil smuggling, financial swap arrangements, cash transfers, exchange-house operations, ship registries and the use of front companies to support Iran.

"Oil smuggling, swap lines, cash transfers, exchange houses, ship registries, front companies - It all needs to stop NOW. You know who you are."

Calling the campaign "an ECONOMIC D-DAY," Trump urged US allies to join Washington in isolating Iran and confronting what he described as the Iranian threat.

"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."

Trump said the measures would severely undermine Tehran's ability to operate internationally and reiterated his opposition to Iran obtaining nuclear weapons.

"These maniacs are on the ropes, and these HISTORIC MEASURES will cripple them and their ability to project terror worldwide. IRAN WILL NEVER HAVE A NUCLEAR WEAPON."

The post came hours after Trump suggested in a conversation with reporters that the strategic importance of the Strait of Hormuz could decline as alternative energy infrastructure expands.

“Record numbers of pipelines are being built. So I think the Hormuz Strait is not going to be quite as important as it was in the past," Trump said.

Asked about potential sanctions against Iran, Trump said the United States has extensive measures available.

“We have things that we could sanction on Iran. We have very draconian sanctions, and we’ll see what happens."

His comments followed a Truth Social post Tuesday in which he said there were no negotiations underway with Tehran as the 60-day negotiating window came to an end.

"There are no talks or conversations going on, or scheduled, with the Islamic Republic of Iran. The Naval Blockade remains in full force and effect. The Hormuz Strait is open and operating. All water mines have been removed or detonated."

Trump's statement appeared to conflict with comments he had previously made to Fox News indicating that a secret channel between Washington and Iran's Islamic Revolutionary Guard Corps was being used for peace discussions.

The IRGC denied that such a channel exists. Its spokesperson, Hossein Mohebbi, told the semi-official Tasnim news agency that Trump's claim was a "delusion" and said there were no discussions between IRGC officials and American representatives.

Mohebbi also said Iran's official diplomatic bodies were not negotiating with Washington, attributing the lack of dialogue to what he called Washington's "breach of promises."

Iranian Foreign Ministry spokesperson Esmaeil Baghaei separately rejected reports of undisclosed contacts between the United States and the IRGC involving representatives from Iraqi Kurdistan. He also denied reports that a secret US-Iran meeting had taken place in Erbil.

Baghaei characterized the reports as "media techniques and psychological operations used to sow discord among Iran's decision-making bodies".