A day after two explosions over the Kremlin caused a volley of accusations between Ukraine and Russia, the Ukrainian capital was bracing on Thursday for any retaliatory strikes.
The bluster that followed the news of the drones exploding raised fears that Moscow would use Wednesday’s incident to justify intensifying attacks. Russia, blaming Ukraine for what it called an assassination attempt on President Vladimir V. Putin, chose to publicize the incident and said it reserved the right to retaliate.
Early Thursday, it remained unclear who was responsible for the drones, which exploded 15 minutes apart. The United States Embassy in Kyiv issued a warning late Wednesday that there was a heightened risk of Russian missile attacks, including in the Ukrainian capital and surrounding area, citing “the recent uptick in strikes across Ukraine and inflammatory rhetoric from Moscow.”
Ukraine, which typically practices a policy of deliberate ambiguity over whether it has been responsible for attacks inside Russia, denied any responsibility for the drones on Wednesday, with President Volodymyr Zelensky saying Moscow had manufactured the incident to stir up public support.
Mr. Zelensky was in the midst of a rare trip outside Ukraine, arriving in the Netherlands late Wednesday after spending the day meeting with the leaders of Nordic nations in Finland. While in the Netherlands, he was expected to speak at The Hague, visit the International Criminal Court and meet with Prime Minister Mark Rutte in Amsterdam on Thursday, according to Dutch media reports.
Mr. Zelensky has long urged that Mr. Putin and the officials who helped bring war to Ukraine be held accountable by international law. He and other Ukrainian officials have proposed that European leaders set up a tribunal for that purpose, one that could work alongside the International Criminal Court but bypass its long, onerous prosecution process. Mr. Zelensky referred to such a tribunal on Wednesday.
“We didn’t attack Putin,” he said. And as for the Russian leader’s fate, he said, “We leave it to the tribunal.”
Ukraine’s preparations for an expected counteroffensive have been underway for weeks. Mykhailo Podolyak, an adviser to Mr. Zelensky, suggested on Wednesday that Russia could have staged the drone attack to justify launching a “large-scale terrorist provocation” against Ukraine in the coming days.
Mr. Putin is set to preside over a military parade on Tuesday, Russia’s main patriotic holiday known as Victory Day — the celebration of the Soviet Union’s World War II victory over Nazi Germany.
The air raid sirens that had wailed in Kyiv three of the previous six nights rang out again early on Thursday. Three loud booms were heard about 2:30 a.m. It was not known whether the sounds were air defense weapons exploding in the sky or missiles hitting targets.
Marc Santora, Andrew E. Kramer and Johanna Lemola contributed reporting.
