(CNN) - The Trump administration ratcheted up pressure on Iran Wednesday, announcing a reward program to disrupt Tehran's financial operations as well as confirming it had offered to pay tanker captains if they helped the United States impound Iranian vessels carrying Iranian oil and unveiling a new wave of sanctions.
The administration also signaled it is not likely to grant the waivers France needs to create a multi-billion dollar line of credit to Iran, part of a European effort to offset the pain caused by US sanctions and keep the 2015 nuclear deal alive.
"We can't make it any more clear that we are committed to this campaign of maximum pressure and we are not looking to grant any exceptions or waivers," Brian Hook, the US special representative for Iran, said at the State Department.
Hook poured cold water on the French proposal as the US unveiled new sanctions against Iran's "oil for terror network" and announced a $15 million reward program to disrupt the financial operations of Iran's Revolutionary Guard Corps.
In a reflection of the US focus on curtailing Iran's oil revenues, a State Department official also confirmed Wednesday that Hook had offered millions of dollars to about a dozen tanker captains if they helped the US impound their vessels, which were carrying Iranian oil.
US officials announced the new measures as President Donald Trump said that he would not agree to the condition laid out by Iranian President Hassan Rouhani last month that the US drop sanctions before talks begin.
'That's not happening'
"That's not happening -- that won't be happening," Trump said during a Wednesday briefing in the Oval Office. The President claimed that the US is "not looking for regime change," but suggested painful US measures are to come. "I can't imagine they're going to want to go through what they're going to have to go through if they do it the hard way," he warned.
Hook echoed that theme, telling reporters that the US is "going to intensify our maximum pressure campaign because Iran, we need to deny it the revenue it needs to fund its foreign policy. It's also the principle means by which you bring Iran back to the negotiating table."
"Iran never comes back to the negotiating table without diplomatic isolation, economic pressure or the threat of military force, that's just been the history of it, so we will continue as we have today," Hook continued. "We think that this creates the right atmosphere that will lead eventually to talks, but that's a decision that the Iranians have to make."
The US unveiled the new measures as French President Emmanuel Macron has been spearheading an effort to extend the line of credit to Iran and stand up a trade mechanism meant to help Iran access food and medicine.
Hook stressed that the US has seen "no concrete proposal" from France on the line of credit, while another senior administration official, speaking to reporters on background, said "the French have been trying to cook up these schemes for the past year now."
France and other European nations have struggled to mediate growing tensions between Iran and the US since Trump left the nuclear deal in 2018 and steadily escalated US sanctions against Tehran.
Iran has responded in recent months by breaching some of the deal's limits on nuclear material and set a Sept. 6 deadline to further dial back its nuclear commitments unless Europe finds a way to help Iran gain some benefit from the international pact.
US sanctions against Iran's oil exports have hit particularly hard and on Wednesday, US officials announced new Treasury Department actions to restrict Iran's oil exports that they said benefit the Syrian regime and others.
The measures impose a rash of penalties on a network of ship managers and vessels, and threaten consequences for those who support their efforts.
"Every port operator, ship owner and management company should steer clear of the targets identified today," Hook said at the State Department. "The economic and reputational cost that result from US sanctions are not worth the modest gains of doing business with Iran."
Later, he warned that "the criminal liability and immigration consequences of crewing Iranian tankers are real and not worth the risk."
The Trump administration claims that the Iranian regime has been leveraging the Revolutionary Guard Corps, or IRGC, to hide and sell hundreds of millions of dollars of oil. US officials said Wednesday that in the spring of 2019, a network led by the IRGC and its Quds Force -- the elite unit tasked with overseas operations -- used more than a dozen tankers to transport nearly 10 million barrels of crude oil, largely to the Syrian regime, but also to China.
The Treasury Department said these shipments were sold for more than half a billion dollars.
"Treasury's action against this sprawling petroleum network makes it explicitly clear that those purchasing Iranian oil are directly supporting Iran's militant and terrorist arm, the IRGC-Quds Force," said Treasury Secretary Steven Mnuchin in a statement. "Our actions over the last two weeks should serve as a strong warning to anyone considering facilitating the Quds Force's oil sales that there will be swift consequences."
Hook also unveiled a reward program for anyone who provides tips that help disrupt the IRGC's financial operations and its oil trade. Hook made the announcement as the Financial Times reported that he had directly offered several millions of dollars to about a dozen ship captains whose vessels were carrying Iranian oil if they would help the US impound them.
A State Department official confirmed to CNN that Hook made the offers by email and text message suggesting the captains would be paid if they redirected the tankers to a country that would impound them on behalf of the US.
The official said that the captains were "warned" of the consequences if they did not comply with Hook's offer. In the case of the Iranian Grace 1 tanker, which was seized and then released by authorities in Gibraltar, Captain Akhilesh Kumar did not reply to Hook's offer and was then sanctioned by the US, the official said.
A State Department spokesperson, speaking on background about the Financial Times story, confirmed "the details are accurate."
"We have conducted extensive outreach to several ship captains as well as shipping companies warning them of the consequences of providing support to a Foreign Terrorist Organization," the spokesperson said.
On Wednesday, Hook said the US was urging "any person with information that leads to the disruption of Iran's petroleum shipping network to contact us."
'Use your imagination'
The State Department's "Rewards for Justice" program has previously been used to offer incentives to people to help prevent acts of terrorism. Hook said that his announcement was "historic" because it is the first time the US has ever deployed the program to target a government entity's financial operations.
He said that the IRGC operates "more like a terrorism operation than a government" entity.
Asked for examples of what sort of tip could yield part of the $15 million payout, Hook said, "there are so many touch points along the chain that moves from when the oil is loaded and when it reaches its destination, the crews, the captains, the people who re-provision ships, there are many people who are involved in that and it's often the tips that you don't think are going to lead to something big that often do."
"Use your imagination," he added. "There are many possibilities"
CNN's Betsy Klein, Michael Conte and Jamie Crawford contributed to this report
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