Pope Francis arrived in the United States on Tuesday for his first visit -- a historic six-day trip during which his focus on consumerism, poverty and the marginalized risks appearing as a criticism of American society.
The 78-year-old Argentine pontiff stepped onto US soil for the first time at Andrews Air Force Base outside Washington, where he was greeted by US President Barack Obama, his wife Michelle and their two daughters, after making a tour of communist-ruled Cuba.
US Catholic leaders and a select crowd of several hundred well-wishers were on hand to greet the pope, who wore his traditional papal whites and waved to the crowd, who chanted: "Ho ho, hey hey, welcome to the USA."
A small group of children from Catholic schools in the Washington area were brought forward to welcome the pontiff.
Obama will host the Jesuit pope at the White House on Wednesday.
"When the president sits down with Pope Francis tomorrow in the Oval Office, the president will not arrive at that meeting with a political agenda," White House spokesperson Josh Earnest told reporters.
"This is an opportunity for two men who have so many values in common to talk about the efforts that they are making in their respective and quite different roles to advance those shared values."
Asked at a briefing why Obama has gone to "these lengths" to greet the pope, Earnest said "Pope Francis, we have seen, has really struck a chord in people not just across the United States but around the world. He serves as a source of inspiration not just for Catholics but of people of frankly all religions around the world."
Francis will make two key speeches during his visit, addressing Congress on Thursday and the United Nations on Friday.
On the plane from Cuba to the United States, the pope told reporters that he would not specifically raise Washington's embargo on Havana in his speech before American lawmakers, but expressed his opposition to it.
"The Holy See is against this embargo, but it is against all embargoes," he said.
Other topics in his addresses will include critiques of the dominance of finance and technology; a condemnation of world powers over the conflicts gripping the planet; appeals to protect and welcome immigrants; and climate change, according to Vatican sources.
On Tuesday, he traveled in a Fiat 500 to the Vatican's diplomatic mission in Washington, where he will be staying, eschewing larger, more polluting vehicles.
The visit will take place under tight security, with US authorities on top alert to handle the complexities of protecting a pope who insists on traveling in an open vehicle to be closer to the masses.
Authorities are facing a particular security headache in New York, where Francis plans to criss-cross Manhattan at a time when 170 world leaders will be in town for the UN General Assembly.
He will preside over an inter-faith ceremony at Ground Zero, visit a Harlem Catholic school and greet crowds on a procession through Central Park. He will wrap up his trip Saturday and Sunday in Philadelphia at an international festival of Catholic families.
The pope arrives in the United States after four days in Cuba, where he said three masses before adoring crowds and met President Raul Castro and his brother Fidel, the men who have ruled the island since its 1959 revolution.
The pontiff, the first from Latin America, played a key role in brokering the recent rapprochement between Washington and Havana, which resulted in the restoration of diplomatic ties in July after more than half a century.
In the United States he will find an American public that widely respects him, but has a less favorable view of the Catholic Church.
While 81% of Catholics have a positive view of the Church, only 55% of America's roughly 70 million Catholics as a whole do, according to a poll conducted by The Washington Post and ABC News earlier this month.
And for some critics, the dominant themes of his papacy -- his critique of consumerism, calls to embrace poverty and condemnation of a "throwaway culture" -- sound remarkably like an indictment of the American way of life.
That was underlined ahead of his trip when Republican Congressman Paul Gosar, who is Catholic, declared he would boycott the pontiff's historic address to Congress to protest his "leftist" views.
The pope has been active in urging compassion, including for those historically shunned by the Church, and for calling for action against economic inequality and environmental degradation.
Americans in general approve of those efforts, with 54% wanting him to "continue as he has been" and another 23% urging him to be even more active.
During his Cuba visit, Francis discreetly refrained from chastising the communist regime for its crackdowns on dissidents and curbs on civil liberties.
Before leaving the island on Tuesday, Francis said mass in Cuba's second city Santiago, cradle of the Castros' uprising against dictator Fulgencio Batista, calling for a new kind of "revolution."
He urged Cubans "to build bridges, break down walls, sow seeds of reconciliation," in comments that appeared to allude to the nascent reconciliation across the Florida Straits.