Alternate links: Google News | Twitter
In his latest implicit rebuke to Donald Trump, the first US leader of the Roman Catholic church said the word "America" had become a "byword for freedom" across the world because of the way the country welcomed migrants.
In a speech given live from the Vatican to the National Constitution Center in Philadelphia as he received the Center's Liberty Medal, Leo said he hoped that ideals of "unity, justice and peace" held by the founding fathers would guide the US as it celebrated its 250th anniversary.
"This historic anniversary presents us with the opportunity to reflect once again on the nation's founding principles in the hope that America will remain ever true to the dream that has earned it the title of land of the free and home of the brave," the pope said.