The United Nations' highest court on Wednesday ordered Russia to stop hostilities in Ukraine.
The International Court of Justice, or ICJ, granted measures requested by Kyiv although many are sceptical that Russia will comply.
Two weeks ago, Ukraine asked the ICJ -- also known as the World Court -- to intervene, arguing Russia violated the 1948 Genocide Convention by falsely accusing Ukraine of committing one and using that as a pretext for the ongoing invasion.
"The Russian Federation shall immediately suspend the special military operations it commenced on 24 February 2022," the court's president, judge Joan E. Donoghue, said.
Countries that refuse to abide by court orders can be referred to the UN Security Council, where Russia holds veto power.
Still, Ukraine President Volodymyr Zelenskyy hailed it as a major breakthrough.
"Ukraine gained a complete victory in its case against Russia at the International Court of Justice," he wrote on Twitter.
"The ICJ ordered to immediately stop the invasion. The order is binding under international law. Russia must comply immediately. Ignoring the order will isolate Russia even further."
The Kremlin not expected to comply
Moscow snubbed a hearing last week when lawyers for Ukraine told the court that Russia had started an "unprovoked aggression".
The invasion brought "cities under siege, civilians under fire [creating a] humanitarian catastrophe and refugees fleeing for their lives," argued David Zionts, a Ukraine legal team member.
Earlier this week, Russia argued in writing that The Hague-based court lacked jurisdiction to hear the case and that nothing in the convention forbids the use of force.
In a 13-2 decision, the court also told Moscow to ensure military units "take no steps" to further the conflict, which Russia refers to as a "special military operation."
The Russian and Chinese judges dissented.
The bar for granting provisional measures is low, says Melanie O'Brien, an associate professor of international law at the University of Western Australia and an expert on the Genocide Convention.
"The court was not being asked to make a decision on the real crux of the case," she told reporters in a briefing ahead of the ruling.
In January, the court ordered Myanmar to prevent genocide against the Rohingya people, a Muslim-minority group that has been persecuted in the country for years.
As with Wednesday's decision, the court also ordered Myanmar to preserve evidence of any crimes and submit regular reports to the court.
Earlier on Wednesday, the International Criminal Court chief prosecutor, Karim Khan, met with the Ukrainian President Volodymyr Zelenskyy in a surprise meeting.
The pair discussed the court's ongoing investigation into possible war crimes in the country.
While the ICJ can hold states responsible, the International Criminal Court could prosecute individuals.
Since the 7 March hearing, Russia has intensified its military strikes on towns and cities across Ukraine, hitting civilian infrastructure across the country, including a deadly strike on a maternity hospital in Mariupol, and sending more than 3 million refugees fleeing across borders.
The Ukrainian State Prosecutor's Office said it was starting a pre-trial investigation after it received information that the Russian forces opened fire at a group of civilians in line for bread in Chernihiv on Wednesday, killing ten people.