(Bloomberg) -- The U.S. sanctioned a shipping network controlled by Iran’s Islamic Revolutionary Guard Corps on Wednesday, saying it has helped move hundreds of millions of dollars of oil to the militant group Hezbollah, Syrian President Bashar al-Assad’s regime and other illicit actors.

The Treasury Department designated about 16 entities and 10 individuals to its sanctions list, according to a release on its website. Treasury’s Office of Foreign Assets Control also issued an advisory warning of the sanctions risks related to oil shipments to Syria, including those from Iran.

“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,” Treasury Secretary Steven Mnuchin said in a statement.

The sanctions mark the latest step in the U.S.’s effort to ratchet up pressure on Iran over its nuclear program, even as European countries seek to broker a deal that would salvage a 2015 nuclear accord the U.S. quit last year. President Donald Trump said last week he’d be willing to meet Iranian President Hassan Rouhani under the “correct” circumstances.

But the U.S. messaging has been muddled and the administration has continued to ramp up pressure on the Islamic Republic. On Tuesday, Treasury announced sanctions against the Iran Space Agency and two affiliated research groups, accusing them of advancing Tehran’s missile programs. A senior administration official said Wednesday that the U.S. is offering a reward of up to $15 million for anyone who helps disrupt the financial operations of Iran’s Revolutionary Guard Corps and Quds Force.

French Finance Minister Bruno Le Maire met with U.S. authorities in Washington earlier this week as part of a plan to offer Iran a $15 billion economic lifeline, according to French officials, an idea a Trump administration official said was a non-starter. The U.S. special envoy for Iran, Brian Hook, is expected to brief reporters at 11 a.m. in Washington.

Amid all the shuttle diplomacy by the French, Iranian officials have been threatening to ramp up their nuclear activities this week in a further violation of the nuclear deal. French officials have said such a move would be sending the wrong signal.

Wednesday’s sanctions against the shipping network also come shortly after a tanker carrying Iranian crude disappeared from satellite-tracking not far from Syria’s coast. The disappearance prompted speculation that the ship was about to transfer its cargo to another vessel out of the view of global ship-monitoring systems.

The last signal from the supertanker Adrian Darya 1, thought to have 2 million barrels of oil on board, was received on Monday afternoon, according to ship-tracking data compiled by Bloomberg.

Previously called Grace 1, the vessel was seized near Gibraltar by the U.K. military and local police in early July on suspicion of supplying crude to Syria. The British overseas territory released the carrier last month, saying it received assurances the vessel wouldn’t sail to any entity sanctioned by the European Union.

To contact the reporter on this story: Saleha Mohsin in Washington at smohsin2@bloomberg.net

To contact the editors responsible for this story: Joshua Gallu at jgallu@bloomberg.net, ;Alex Wayne at awayne3@bloomberg.net, Bill Faries

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