STORY: After deadly explosions rocked a Russian air base in the annexed Crimean peninsula on Tuesday, and questions arose over who or what caused the incident, Ukraine denied responsibility for the event deep inside Russian-occupied territory.
Witnesses said they heard at least 12 blasts.
Video obtained by Reuters showed a plume of smoke stretching into the sky.
Crimea's health department, along with the Russian governor of Crimea, said at least one civilian had been killed and multiple others injured.
But the cause of the blasts are still unclear.
Russia's defense ministry brushed off the idea there had been an attack, and claimed the blasts came from detonations of stored ammunition.
A senior Ukrainian official suggested it was the work of partisan saboteurs.
While another suggested Russian incompetence as a possible cause.
Crimea is a holiday destination for many Russians.
Moscow annexed the peninsula from Ukraine in 2014, and used it in February as one of the launchpads for its invasion.
Zelenskiy did not directly mention the blasts in his daily video address on Tuesday.
But he said it was right that people were focusing on Crimea.
“The presence of Russian occupiers in Crimea is a threat for all of Europe and to the global stability. The Black Sea region cannot be a safe place while Crimea is occupied."
What Moscow calls a 'special military operation', Ukraine and its allies say is an unprovoked imperial-style war of aggression.
On Tuesday, U.S. President Joe Biden made a move of his own.
Formally endorsing Finland and Sweden joining NATO, the most significant expansion of the military alliance since the 1990s.