MILAN (AP) — Former U.S. President Barack Obama is in Milan to deliver a keynote speech on food security and the environment, two issues that he has long worked on.

The visit was his first public foreign foray since leaving the presidency.

Obama arrived Monday, greeted by former Premier Matteo Renzi, a political ally who is mounting a comeback after resigning when his referendum on constitutional reforms failed.

Renzi welcomed Obama in a Facebook post, calling him "a friend and great leader ... who still has much to say and give to world politics."

Obama made a few tourist stops in Italy's fashion and finance capital before attending a dinner hosted by an Italian think tank attended by friends and business leaders. He will give a speech on food security on Tuesday afternoon.