Russia was responsible for "serious failings" in its handling of the 2004 Beslan school siege by Chechen rebels in which over 330 people were killed, many of them children, the European Court of Human Rights (ECHR) ruled Thursday.
Although Russian authorities had information that an attack was being planned on a school in North Ossetia, the court found they failed to do enough to disrupt the plot and had not sufficiently protected the hostages.
Survivors and relatives of the victims who brought the case to the Strasbourg-based court hailed the decision, saying they felt their voices had finally been heard.
"For us it has been 12 years of searching for the truth, of us striving to be heard, striving to tell the truth about Beslan. They have heard us," Susanna Dudiyeva, whose 13-year-old son Zaur was killed in the attack, told AFP.
But the Kremlin reacted furiously to the judgement, saying it was "absolutely unacceptable".
The Russian justice ministry immediately announced plans to challenge the ruling in a higher chamber of the ECHR, arguing that a number of the court's conclusions were "not backed up". It has three months to appeal.
Militants demanding the withdrawal of Russian troops from the war-torn republic of Chechnya attacked the school on September 1, 2004.
The attackers herded 1,100 people including 800 children into a gymnasium and rigged the building with explosives.
After three days of fruitless negotiations, explosions in the school prompted Russian security forces to storm the gymnasium.
A total of 186 children were among the more than 330 people who lost their lives in one of the deadliest hostage crises in history.
- 'Insufficient steps' -
Russian officials insist they took the best course of action faced with armed extremists, but many survivors and victims' relatives believe the security services were to blame for the firefight.
"The authorities had been in possession of sufficiently specific information of a planned terrorist attack in the area, linked to an educational institution," the court said.
"Nevertheless, not enough had been done to disrupt the terrorists meeting and preparing."
The judges found that "insufficient steps had been taken to prevent (the attackers) travelling on the day of the attack; security at the school had not been increased; and neither the school nor the public had been warned of the threat".
- 'Lethal force' -
The court found that through its actions, the Russian state had violated Article 2 of the European Convention of Human Rights, which guarantees a right to life.
There was an additional violation in the use of "lethal force by security forces".
"In the absence of proper legal rules, powerful weapons such as tank cannon grenade launchers and flame-throwers had been used on the school," which contributed to the casualties among the hostages, the court said.
The judges also said there were "serious shortcomings" in the investigation into the attack, especially that there had been "no proper examination of how the victims had died".
The claimants in the case say authorities were primarily seeking to eliminate the attackers, and gave little care to avoiding killing hostages.
Their lawyers have particularly criticised the lack of in-depth autopsies on the bodies of 116 victims found burned in the gymnasium.
The ECHR ordered Russia to pay a total of three million euros ($3.2 million) in compensation to 409 surviving hostages and relatives of the deceased.
"It's good this ruling has been passed -- I think that conclusions will be drawn so that something like this does not happen again," said lawyer Sergei Knyazkin, who represented relatives of victims.
He said that awarded compensation was "small", ranging from 5,000 to 20,000 euros ($5,300 to $21,250) per person.
The Beslan massacre was one of a string of brutal attacks Russia suffered in the 1990s and 2000s stemming mainly from an insurgency in Chechnya that morphed from a separatist rebellion into an Islamist campaign.
There were two separatist wars in Chechnya in the 1990s and 2000s, but violence in the region has largely been suppressed under the iron-fisted rule of strongman leader Ramzan Kadyrov.
However, the overwhelmingly Muslim Russian North Caucasus has emerged as one of the major sources of foreign jihadists fighting in Syria and Iraq.