The International Court of Justice (ICJ) ordered Russia on Wednesday to stop the military actions it started in Ukraine on Feb. 24. President Zelensky demanded Russian must comply.
"The Russian Federation shall immediately suspend the military operations that it commenced on Feb 24, 2022 in the territory of Ukraine," the judges said.
The judges added Russia must also ensure that other forces under its control or supported by Moscow should not continue the military operation.
Ukrainian President Volodymyr Zelensky said on Wednesday that peace talks were beginning to sound more realistic but that more time is needed as Russian airstrikes killed five people in Kyiv and the refugee tally from Moscow's invasion reached 3 million.
Ukrainian officials have raised hopes the war could end sooner than expected, possibly by May, saying that Moscow may be coming to terms with its failure to impose a new government by force and running out of fresh troops.
"The meetings continue, and, I am informed, the positions during the negotiations already sound more realistic. But time is still needed for the decisions to be in the interests of Ukraine," Zelensky said in a video address ahead of the next round of talks.
In a hint of a possible compromise, Zelensky said earlier that Ukraine was prepared to accept security guarantees from the West that stop short of its long-term goal of joining NATO. Moscow sees any future Ukraine membership of the Western alliance as a threat and has demanded guarantees it will never join.
Kremlin spokesperson Dmitry Peskov said it was too early to predict progress in the talks. "The work is difficult, and in the current situation the very fact that (the talks) are continuing is probably positive."
US President Joe Biden will make his first visit to Europe since Russia invaded Ukraine to discuss the crisis with NATO allies next week, the White House said.
Leaders and representatives of the government have begun to fly directly to Kyiv to meet with Ukrainian President Zelensky and show their solidarity. Polish Prime Minister Mateusz Morawiecki, Polish Deputy Prime Minister Jaroslaw Kaczynski, Czech Prime Minister Petr Fiala and Slovenian Prime Minister Janez Janša met with Zelensky on Wednesday.
"At a time when many ambassadors have left Ukraine in connection with the full-scale invasion of the Russian Federation, these dignitaries, leaders of their beautiful independent European states, fear nothing, care for our fate more, and they are here to support us," said Zelensky. "This is a great courageous, correct and friendly step. And I am sure that with such friends, with such countries, with such neighbors and partners, we will really be able to win."
Turkish Foreign Minister Mevlut Cavusoglu will also visit Kyiv on Thursday, after having met his Russian counterpart Sergei Lavrov in Moscow on Wednesday.