Pope Francis on Monday denounced the killing of civilians amid ongoing conflicts around the world, including in Gaza and Ukraine.

In an address to diplomats accredited to the Vatican, the head of the Catholic Church said “modern wars no longer take place only on clearly defined battlefields, nor do they involve soldiers alone.”

The pope delivered a warning to aggressor nations: “In a context where it appears that the distinction between military and civil objectives is no longer respected, there is no conflict that does not end up in some way indiscriminately striking the civilian population,” he said, adding, “the events in Ukraine and Gaza are clear proof of this.”

“We must not forget that grave violations of international humanitarian law are war crimes, and that it is not sufficient to point them out, but also necessary to prevent them,” he added.

The pope’s remarks come as Israel continues military strikes against Palestinians, killing at least seven civilians in Jenin City in the occupied West Bank and two journalists in southern Gaza on Sunday.

South Africa has brought a case accusing Israel of genocide in Gaza to the International Court of Justice in The Hague, the highest U.N. court, which will hold hearings this week.

Pope Francis condemned Hamas’ violent attack against Israel on October 7, which he said provoked a “strong Israeli military response in Gaza which has led to the death of tens of thousands of Palestinians, mainly civilians, including many young people and children, and has caused an exceptionally grave humanitarian crisis and inconceivable suffering.”

“This is not the way to resolve disputes between peoples; those disputes are only aggravated and cause suffering for everyone,” he said, renewing his appeal for a cease-fire “on every front, including Lebanon, and the immediate liberation of all the hostages held in Gaza.”

Referring to the Kremlin’s war on Ukraine, the pope said “the greatly desired peace has not yet managed to take root in minds and hearts after nearly two years of large-scale war waged by Russia against Ukraine despite the great numbers of victims and the massive destruction.”