Andrews Air Force Base, Md. ? Pope Benedict XVI stepped onto U.S. soil for the time as pontiff Tuesday, arriving to a presidential handshake and wild cheering only hours after he admitted that he is “deeply ashamed” of the clergy sex abuse scandal that has devastated the American church.

Benedict gave hundreds of spectators a two-handed wave as he stepped off a special Alitalia airliner that brought him from Rome. Students from a local Catholic school screamed ecstatically when they saw the pope, who shook hands warmly with President Bush, first lady Laura Bush and their daughter Jenna on the tarmac.

Hundreds of onlookers clapped and shouted as they watched the scene from nearby bleachers.

Benedict tackled the most painful issue facing the U.S. Catholic Church – clergy sex abuse – on his flight to America. The U.S. church has paid out $2 billion in abuse costs since 1950, most of that in just the last six years.

The pope spoke in English as he answered questions submitted in advance by reporters.

“It is a great suffering for the church in the United States and for the church in general and for me personally that this could happen,” Benedict said. “It is difficult for me to understand how it was possible that priests betray in this way their mission … to these children.”

“I am deeply ashamed, and we will do what is possible so this cannot happen again in the future,” the pope said.

Benedict pledged that pedophiles would not be priests in the Catholic Church. “We will absolutely exclude pedophiles from the sacred ministry. It is more important to have good priests than many priests. We will do everything possible to heal this wound.”

Benedict’s pilgrimage is the first trip by a pontiff to the United States since the Boston case in 2002 triggered a crisis that spread throughout the United States and beyond.

As head of the Vatican agency that enforces adherence to Catholic doctrine, then-Cardinal Joseph Ratzinger was heavily involved in gaining Vatican approval for the reforms U.S. bishops proposed for the American church. The bishops have since released several reports analyzing the scandal and have pledged that all credibly accused priests will be pulled from public ministry.

Benedict described his pilgrimage as a journey to meet a “great people and a great church.” He spoke about the American model of religious values within a system of separation of church and state.

President Bush made the unusual gesture of greeting Benedict at Andrews Air Force Base – the first time he has welcomed a foreign leader there. The two will meet again today, when a crowd of 9,000 or more is expected at the White House to greet Benedict on his 81st birthday.