Tehran is confronting Washington at the top court over frozen assets worth around $2 billion, in a case that could deepen Donald Trump administration’s rift with international justice.
In today’s hearing, a 15-judge bench is listening to arguments by Washington's lawyers.
Planned to continue for four consecutive days, today’s session started only a week after the ICJ, in a separate case, ordered the US to ease sanctions reimposed after President Donald Trump pulled out of the 2015 nuclear deal with Iran.
Both the assets and the sanctions cases are based on a 1955 "Treaty of Amity" between Washington and Tehran that pre-dates Iran's Islamic Revolution.
Iran is also suing Washington over breaking away with the 1955 treaty, calling for the US "to make full reparations to Iran for the violation of its international legal obligations."
Last Wednesday the Trump administration announced it was not only tearing up the 1955 treaty but also that it was quitting the international accord relating to the UN top court's jurisdiction.
However, Iran won a victory last week when the ICJ ruled that the US must lift sanctions against Tehran targeting humanitarian goods like food and medicine.
It remains unclear how Washington will respond to the latest case before the court but US officials confirmed that their lawyers will be present at the hearing on Monday.
A decision by the ICJ's judges could take weeks or even months before being made public.
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