Speaking in Pompei on Friday, the first US pope marked a year leading the 1.4-billion-member Catholic Church, a day after meeting US Secretary of State Marco Rubio.
He urged worshippers to pray governments turn from violence, warning peace is threatened by international tensions and an economy that favours the arms trade over human life.
The Vatican said Leo and Rubio pledged to improve bilateral relations after tensions with Washington, as Donald Trump has attacked the pontiff over his criticism of the Iran war.
As the first American pope, how will his unique background shape his global campaign for 'wild peace'?
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