Pope Francis warned there are so many conflicts now that we are on the brink of World War III, indicating that humankind has not learned any lessons from the first World War.

"War is madness," the pontiff said Saturday at an Italian service commemorating the 100th anniversary of World War I, the BBC reported. His homily was delivered at Redipuglia cemetery, where 100,000 Italian soldiers who were killed during the first war are buried. About 60,000 of them remain unidentified.

"Even today, after the second failure of another world war, perhaps one can speak of a third war, one fought piecemeal, with crimes, massacres, destruction," Pope Francis said.

Hours after his speech, the Sunni jihadist group the Islamic State, or ISIS, reportedly released a video of the beheading of 44-year-old British aid worker David Haines, the third slain hostage in less than a month.

President Barack Obama recently announced plans to step up military intervention in northern Iraq and Syria, where the militants have terrorized and killed civilians in a seemingly never-ending campaign to enforce strict Islamic rule.

In Ukraine, the first of weapons from NATO countries have been delivered to help government troops fight pro-Russian separatists in an ongoing conflict, said to have created the worst strain on relations between the West and Russia since the Cold War. Western powers have accused Russia of providing weapons and troops for the uprising, which Moscow denies.

Conflicts like these have prompted Pope Francis to urge for international peace in recent months, including in Gaza and Africa as well as Iraq and Syria.

"Humanity needs to weep, and this is the time to weep," the pontiff said.

The visit to Italy had personal meaning for the pope, the BBC reported. His grandfather fought in Italy's offensive against the Austro-Hungarian empire in 1917 and 1918. The pope's grandfather survived the war.