Washington, USA - Pope Benedict and President George W. Bush disagree on the Iraq war and other foreign policy issues, but their White House meeting this week may focus more on areas of agreement like abortion.
The Vatican strongly opposed the Iraq war which it believed did not follow the Catholic "just war" doctrine which justifies defensive conflicts but not preemptive attacks, analysts say.
Bush argued that the U.S.-invasion of Iraq in 2003 was necessary to remove a threat from Saddam Hussein and help spread democracy in the Middle East.
The war will likely come up in the talks but no public statement is expected because the pope usually avoids conflict with leaders of countries he visits. Pope Benedict has been deeply concerned about the Iraq situation, especially the plight of minority Christians and the death of a Chaldean archbishop who was kidnapped by gunmen.
"From the beginning the Vatican had serious concerns about the appropriateness of the war," said Stephen Schneck, a political scientist at Catholic University.
In other foreign policy differences, the Vatican has diplomatic relations with Cuba, supports dialogue with Iran and Syria and is more enthusiastic about working through the United Nations and other international bodies.
"The Vatican's approach is you should talk to everybody, talking never hurts you. And you try and find peaceful solutions to these problems," said Rev. Thomas Reese, a Georgetown University theologian. "The Vatican has always been a strong supporter of the United Nations, of multilateral, multinational approaches to problems."
Both seek an Israeli-Palestinian settlement. Bush is pushing for an agreement in his last year in office, having visited Israel and the West Bank for the first time as president.
The two men present contrasting personalities and management styles.
"He (the pope) really does have a European's outlook on the world. And that of course is quite different from the way the Bush administration looks at the world," Schneck said.
The affable Bush sets great store in personal relationships and distrusts academics while the German-born Benedict, a theoretician and theologian, rose through church ranks on the basis of his intellectual brilliance.
"The pope is somebody who came through the ranks in an institution that is very hierarchical, very structured, very legalistically oriented," Schneck said. "And so he's an institution man and therefore tends to give deference to procedures by which institutions operate."
"In contrast, I think President Bush prefers a more personal approach, he likes the direct one-on-one, mano-a-mano kind of approach."
Bush, a Methodist, and the pope both oppose abortion, euthanasia and embryonic stem cell research. But they differ on the death penalty, which Bush supports while the Catholic Church opposes in almost all cases.
Benedict recently praised "the American people's historic appreciation of the role of religion in shaping public discourse and in shedding light on the inherent moral dimension of social issues."
Regardless of their differences, the United States must maintain a relationship with the Vatican, said John Green of the Pew Forum on Religion and Public Life.
"The United States and the Roman Catholic Church have to deal with each other, whether they see eye-to-eye or not," he said. "This kind of meeting presents an opportunity for these leaders to get to know each other, to talk about things, maybe to say some things to each other that they wouldn't want to say publicly."
The two met for the first time last June at the Vatican and discussed the Middle East, aid to Africa and the Iraq war.
Bush greets Pope Benedict at Andrews Air Force Base on his arrival on Tuesday and will hold a special South Lawn ceremony, a private Oval Office meeting, and then a dinner for the pontiff at the White House on Wednesday, which happens to be the pope's 81st birthday.