Polio vaccines for more than 1 million people have been delivered to Gaza, Israel's military said Sunday, after the first confirmed case of the disease in the territory in a quarter-century.

It was not immediately clear how, or how quickly, the more than 25,000 vials of vaccine would be distributed in Gaza, where ongoing fighting and unrest have challenged humanitarian efforts during more than 10 months of war.

Iran’s foreign minister again has referenced his country’s planned retaliation over the assassination of Hamas leader Ismail Haniyeh in Tehran, but called for restraint "to stop the cycle of military actions in the region," including in Lebanon.

Abbas Araghchi said late Sunday he made the remark in a conversation with Italian Foreign Minister Antonio Tajani by telephone.

Russia unleashed a massive drone and missile barrage throughout Ukraine on Monday that appeared to target energy infrastructure. At least three people were reported killed.

The barrage began around midnight and continued beyond daybreak in what appeared to be Russia's biggest attack against Ukraine in weeks.

The ferocious exchange of fire by Hezbollah and the Israeli military is raising fears of a regional war beyond the tense border.

The risks for Lebanon are far greater than in 2006, when a monthlong war with Israel ended in a draw. Lebanon has struggled with years of political and economic crises that left it indebted, without a stable electricity supply, a proper banking system and with rampant poverty.

Five-time former Lebanese Prime Minister Salim Hoss, who served during some of the most tumultuous years of his country's modern history, died Sunday at age 94, the current premier said.

Caretaker Prime Minister Najib Mikati described Hoss, who was also a former government minister and member of parliament, as the "conscience of Lebanon" in a statement announcing his death. He added that Hoss "passed away at the most difficult and delicate stage in which Lebanon needs its conscience."

Danny Citrinowicz, an expert at Israel’s Institute for National Security Studies, said Hezbollah might be trying to “balance the equation without escalating into war” after its response against Israel on Sunday.

Each side hopes their narrative will be sufficient for them to declare victory and avoid a wider confrontation, he said.

After an emergency government meeting on Sunday, Lebanon’s caretaker Economy Minister Amin Salam said officials were “feeling a bit more optimistic” about a de-escalation between Israel and Hezbollah.

“We feel more reassured since both sides confirmed that the expected operations ended,” he said, referring to Sunday morning's heavy exchange of hostilities between Israel and Hezbollah.

A 26-year-old man has turned himself into police, saying he was responsible for the Solingen knife attack that left three dead and eight wounded at a festival marking the city's 650th anniversary, German authorities announced early Sunday.

Duesseldorf police said in a joint statement with the prosecutor's office that the man "stated that he was responsible for the attack."

Israel and Hezbollah on Sunday launched their heaviest exchange of fire after months of strikes and counterstrikes, raising fears of an all-out war that could potentially draw in the United States, Iran and militant groups across the region.

By mid-morning, it appeared the exchange of fire had ended, with both sides saying they had only aimed at military targets. Lebanese authorities said the Israeli strikes killed three people, while there were no reports of casualties on the Israeli side. The situation remained tense.

A spokesman for the U.S. National Security Council, Sean Savett, said Sunday that President Joe Biden was “closely monitoring events in Israel and Lebanon,” after Hezbollah said it fired hundreds of rockets and drones at Israel to avenge Fouad Shukur's killing and Israel said it struck 40 Hezbollah targets in south Lebanon to foil the attack.

“At his direction, senior U.S. officials have been communicating continuously with their Israeli counterparts,” Savett added.