“There is little probability that another war in the most volatile region in the world, where the recent and current experiences of conflict in Syria, Iraq and Yemen are vivid, will succeed in bringing peace to the region."

Beyond relations with Iran and North Korea, the way Mr. Trump is wielding economic and military power will come with collateral costs.

Pope Francis had strongly favored the pact, which sought to integrate Iran into the global economy in exchange for remaining nuclear-free.

"We grew to learn about each other...We grew to see each other as human beings."