Moscow and Kiev have each accused the other of bombarding a nuclear power station under Russian control, heightening concerns of a catastrophe.
In the meantime, President Volodymyr Zelensky urged Ukrainians to be careful before Independence Day festivities.
“Russia could attempt something very revolting and brutal,” he stated in a weekend speech.
“One of the enemy’s primary objectives is to humiliate us,” he continued, “but we must be strong enough to withstand any provocation.”
Sunday’s conference call brought together British Prime Minister Boris Johnson, US Vice President Joe Biden, his French counterpart Emmanuel Macron, and German Chancellor Olaf Scholz to discuss the situation.
Following its conclusion, they advocated military caution around the Russian-controlled Zaporizhzhia nuclear power station in southern Ukraine, where increased fighting has sparked concerns of a catastrophe worse than the 1986 Chernobyl nuclear accident.
The four presidents also stated that they “decided to maintain support for Ukraine’s defense against Russian aggression.”
Nine Russian jets were destroyed earlier this month at a Russian military station on the western coast of Crimea.
29-year-old Darya Dugina perished in a roadside blast outside Moscow.
It is believed that her father, who is known as “Putin’s brain,” was the target of the attack.
Both had attended a patriotic celebration as guests. Putin is thought to have been influenced by Aleksandr Dugin’s writings on the necessity of restoring the Russian empire.