WASHINGTON - Pope Benedict XVI, the spiritual leader of 65 million American Catholics, arrived at Andrews Air Force Base Tuesday, greeted by President Bush and about 800 cheering onlookers.

It was the first time Bush has personally welcomed a dignitary at Andrews. After a few moments in private with the Bushes, the pontiff left in his motorcade without making public remarks after the crowd serenaded him briefly with "Happy Birthday." Benedict turns 81 today.

'ASHAMED' OVER SEX SCANDAL: Even before he touched down, Benedict addressed the hottest issue for many American Catholics: the sexual abuse scandal that has convulsed the church in recent years. Aboard the papal plane, the pontiff said that he is "deeply ashamed" of the Catholic church's clergy sexual abuse scandal and said seminaries will not tolerate pedophiles.

ENCOURAGEMENT FOR THE CHURCH: This is Benedict's first visit to the United States since becoming pope in April 2005. During his five-day journey, he will visit Washington and New York, celebrate two public Masses, address the United Nations and visit ground zero. His agenda for the trip, he said on the flight to Washington, is to bring encouragement and attention to the struggles of the U.S. Catholic Church, to immigrants and their families and to what he sees as the religious foundation of human rights.