The US Treasury Department has sanctioned 17 vessels it says are part of Iran’s ‘shadow fleet’ for oil shipments.

The sanctions were announced on Thursday. Officials said the vessels helped Iran ship millions of barrels of oil and petrochemical products to countries across south and east Asia.

The department said the ships circumvented existing US sanctions. The move targets what it called the regime’s illicit revenue and sanctions-evasion schemes.

‘Treasury is targeting any source of the regime’s illicit revenue,’ the department said in its statement.

The sanctions came as President Trump said the US would not attack Iran before the November midterms. He stressed that the blockade of Iranian ports would remain in full force.

Washington has been tightening the economic screws on Tehran while holding off on new military strikes.

Shadow fleets use old tankers, false flags and ship-to-ship transfers to hide sanctioned oil. Iran’s fleet has grown as enforcement tightened.

The sanctions freeze any US assets of the vessels’ owners and bar Americans from dealing with them.