The sudden death of Pietro Sambi may have a few people wondering. Sambi had a critical role in planning Pope Benedict’s trip to the U.S. (below) in 2008. But that’s just the beginning.
A good explanation, from the USCCB:
The nuncio is the Vatican’s ambassador to the United States. (The United States and the Holy See have had full diplomatic relations since 1984.) Like other ambassadors, Archbishop Sambi represents the Holy See’s views on various issues to the U. S. government. In addition, he acts as a liaison between the Holy See and the Church in the United States. He announces the appointment of new bishops and often attends their ordination or installation as the Vatican’s representative. Since 2006, Archbishop Sambi has attended 35 such events!
The nuncio attends the semi-annual meetings of the United States Conference of Catholic Bishops and addresses the bishops at these meetings.
Archbishop Sambi was the second apostolic nuncio to the United States, succeeding Archbishop Gabriel Montalvo who served from 1998-2006. Prior to 1998, there were two apostolic pro-nuncios and 10 apostolic delegates. The first apostolic delegate to the United States was appointed in 1893.