"Joining the ICC gives Armenia serious tools to prevent war crimes and crimes against humanity on its territory," according to Yeghishe Kirakosyan, Armenia's Foreign Minister.
He said that Armenia's integration into the court "first of all concerns Azerbaijan", referring to two wars with the neighbouring country over the disputed Nagorno-Karabakh region – where Russia deploys peacekeepers.
Neither Azerbaijan nor Russia recognise the ICC, along with other countries including the United States, China and Israel.
How does the ICC relate to the Rome Statute?
The International Criminal Court was established by the Rome Statute, a treaty adopted at a diplomatic conference in the Italian capital on 17 July 1998 and that came into force on 1 July 2002. It outlines the court's functions, jurisdiction and structure.
The statute identifies four core international crimes: genocide, crimes against humanity, war crimes and the crime of aggression. No statute of limitations applies to these offences. According to the Rome Statute, the ICC is authorised to investigate and prosecute these crimes only in situations where states are unable or unwilling to do so themselves.
The court's jurisdiction is complementary to that of domestic courts and extends to crimes committed within the territory of a state party or by a national of a state party. An exception is made for cases where the ICC's jurisdiction is authorised by the United Nations Security Council.
As of November 2023, 124 states were parties to the statute.
Armenia becoming a full-fledged member of the court risks further complicating Yerevan's relationship with Moscow.
Last March, the ICC issued an arrest warrant for Russian President Vladimir Putin over the war in Ukraine and the alleged illegal deportation of children to Russia.
Yerevan is now obligated to arrest the Russian leader if he sets foot on Armenian territory.
But Armenia is also home to a permanent Russian military base and part of a Moscow-led military alliance, the Collective Security Treaty Organisation, which also counts other ex-Soviet republics Belarus, Kazakhstan, Kyrgyzstan and Tajikistan as members.
Moscow called Armenia's accession to the ICC an "absolutely unfriendly step".
Russia's state-owned Tass News Agency quotes Russian Deputy Foreign Minister Mikhail Galuzin as saying that the ICC "has nothing to do with justice; rather, it is a highly politicised pro-Western structure that executes orders to prosecute figures who are undesirable to the West".
Armenian Prime Minister Nikol Pashinyan has tried to reassure Russia that his country is only addressing what it says are war crimes committed by Azerbaijan in their long-running conflict, and is not aiming at Moscow.
But Western countries hailed the ratification, which marks the expansion of the court's jurisdiction into what was long seen as Russia's backyard.
"The world is getting smaller for the autocrat in the Kremlin," European Commission President Ursula von der Leyen said after Armenia ratified the ICC statute in October, referring to Putin.
France also strongly backed Armenia's membership of the ICC.
In November, when Armenia officially applied to join the court, France's Foreign Ministry said it welcomed the move as an "important step towards fighting impunity".
Observers say Armenia could use its membership as a form of deterrent against possible Azerbaijani aggression.
The threat of the court investigating crimes committed as part of any attack on Armenia would "serve as a sword of Damocles of sorts, making Azerbaijan more reluctant to perpetrate acts of aggression against Armenia", legal researcher Mischa Gureghian Hall of the US-based Centre for Truth and Justice told JusticeInfo.net.
To give itself the option of pursuing Azerbaijani soldiers for war crimes allegedly committed during fighting along the border between the two countries in September 2022, the portal noted, Armenia backdated the ICC's jurisdiction to May 2021.