In a world criss-crossed by violent extremism... it is urgent and necessary to defend the ideal of justice for all.
Moscow has never ratified the world's only permanent war crimes court, but in a heavily symbolic move on the opening day of the ICC's annual meeting, it said it was formally withdrawing its signature to the tribunal's founding Rome Statute.
"The court did not live up to the hopes associated with it and did not become truly independent," Russia's foreign ministry said, describing its work as "one-sided and inefficient".
The move came only days after The Gambia on Monday formally notified the United Nations it was leaving the ICC, following in the footsteps of South Africa and Burundi.
"Don't go," pleaded Senegalese politician Sidiki Kaba, the president of the ICC's Assembly of State Parties as he opened an eight-day meeting in The Hague.
"In a world criss-crossed by violent extremism... it is urgent and necessary to defend the ideal of justice for all."
The tribunal opened its doors in 2002 in The Hague as a court of last resort to try the world's worst crimes where national courts are unable or unwilling to act.
But in his passionate plea, Kaba admitted the ICC was undergoing a "difficult moment".
With Russia and China having blocked UN moves to refer war crimes in Syria to the ICC for investigation, Kaba acknowledged some saw "injustice" with international justice marked by "two weights, two measures".
But he offered reassurances, saying: "You have been heard."
There have long been accusations of bias against African nations. And Kenya, Namibia and Uganda have also indicated they are considering pulling out of the Rome Statute.
But chief prosecutor Fatou Bensouda told the assembly her office would continue "to forge ahead to deliver on its important mandate".
"We must not and will not allow that law falls silent during wars and conflicts," she insisted.
"Without the ICC we will regress into an even more turbulent world where chaos and violence take the upper hand."
On the eve of the meeting, Bensouda, who has already opened preliminary probes into cases in the Palestinian territories, Colombia and Ukraine, revealed she may be poised to launch her most complex investigation so far.
If a full-blown investigation goes ahead, the tribunal would be taking on its most politically controversial investigation to date.
And even though the United States has also not ratified the court, US forces will be exposed for the first time to an ICC investigation.
"Though the powerful may fear the court, victims everywhere plead for its involvement," UN human rights chief Zeid Ra'ad Al Hussein said.
He insisted "there is no substitute for the ICC" and in the long-term, "these states will boomerang back as the court is accepted by more and more states".
Warning that "a new trend of isolationist and unprincipled leadership" was sweeping the world, Zeid insisted: "Now is not the time to abandon the post. This is the time of resolve and strength."
"Do not betray the victims, nor your own people. Stand by the Rome Statute and the court. It may not be perfect, in design nor operation... but it is the best we have."
Currently nine out of the 10 full ICC investigations are in African countries. The other is in Georgia.