By Timothy Gardner and Daphne Psaledakis
WASHINGTON, Oct 8 (Reuters) - The US imposed fresh sanctions on Iran on Thursday, targeting individuals, networks and 17 vessels for transporting Iranian crude, oil products and petrochemicals, the Treasury Department said, as Washington stepped up economic pressure on Tehran.
The sanctions are part of the department's "Operation Economic Outcast," which aims to cut Iran's funding for the war with the US, missile construction, cyberattacks and the Islamic Revolutionary Guard Corps, or IRGC.
"Today's action represents the most significant blow yet to Iran's remaining illicit maritime infrastructure by neutralizing the vast majority of the shadow fleet," a Treasury official told reporters on a call. "Treasury is cutting off the regime's last major source of illicit revenue and strengthening international pressure to hold Tehran accountable."
The move tightens the squeeze on Iranian oil sales after the US reimposed its blockade of Iranian ports on July 14 following the breakdown of a memorandum of understanding between Tehran and Washington to end the war.
Iran has only about 20 million barrels of crude oil left on vessels outside the blockade, off Singapore, Malaysia and China, the Treasury official said. The world uses about 100 million barrels of oil per day.
A second Treasury official said Iran has stopped loading and offloading crude oil vessels due to the blockade and sanctions.
President Donald Trump said on social media on Thursday that the US is having "productive discussions" with Iran over the war that began on February 28. Trump said the US will not attack Iran before the midterm elections on November 3.
An analyst said the fact that the US is sanctioning vessels after Iran has delivered virtually all of its oil at sea means the impact will be muted.
"This is economic warfare conducted in the rearview mirror, designed to generate headlines rather than results," said Brett Erickson, a managing principal at Obsidian Risk Advisors.
Vessels targeted by the US sanctions include the Comoros-flagged Paritosh, the Panama-flagged Bitu and the Bahamas-flagged Gas Lucky.
(Reporting by Timothy Gardner and Daphne Psaledakis; Editing by Michelle Nichols, Nia Williams and Paul Simao)
