Ukraine and a trio of other affected countries on January 6 announced their abandonment of a two-year effort to negotiate with Tehran over reparations for a passenger airliner mistakenly shot down by Iran's military in January 2020.
Kyiv joined the governments of Britain, Canada, and Sweden in saying their related coordination group would "now focus on subsequent actions to take to resolve this matter in accordance with international law."
Last month they told Iran it had three weeks to reverse its refusal to address the reparation demands.
"Despite our best efforts over the past two years and multiple attempts to resolve this matter through negotiations, the Coordination Group has determined that further attempts to negotiate with Iran ... are futile," the group said in a statement.
They did not specify what steps they would take to address grievances related to the deaths of their nationals among the 176 people killed when Ukraine International Airlines Flight PS752 was destroyed shortly after takeoff from Tehran.
Iran obfuscated for days but later said its Islamic Revolutionary Guards Corps (IRGC), a branch of the armed forces, accidentally shot down the Boeing 737 because of technical and human error with tensions high between Tehran and the United States.
More than 130 of the passengers had ties to Canada. Citizens or residents of Afghanistan, Britain, Iran, Ukraine, and Sweden were also killed.
Canada said in June that it found no evidence of premeditation in the downing of the airliner.
In May, Human Rights Watch accused Iranian security agencies of harassing and abusing the victims' families to "squash any hope for justice."
A Canadian court last week awarded $84 million and interest to the families of six of the victims.