A tanker carrying $100m (£59m) of Iraqi Kurdish oil is set to be seized by US marshals on Tuesday.
The tanker - carrying an estimated one million barrels of oil - arrived off the coast of Texas on Saturday but had yet to be unloaded.
A US judge approved the seizure request which was sent from the Iraqi government overnight on Monday. Tensions between the Iraqi government and the autonomous Kurdish region have been raised recently.
Earlier in July, Iraqi Kurds took over two oilfields in northern Iraq amid a growing dispute with the government in Baghdad.
The decision by the judge to allow for the seizure is a blow to to the Kurdistan Regional Government (KRG), which has been attempting to establish its own oil sales as one step towards negotiating for eventual independence.