The Holy See—the embodiment in international law of the pope’s mission as universal pastor of the Catholic Church—was a diplomatic actor centuries before the U.S. was founded, or before modern Italy was born. The Holy See plays a unique and often crucial role in world affairs, from John Paul II’s pivotal role in the collapse of European communism, to the important achievements of the Holy See in standing up for human dignity and human rights, and the Vatican’s “honest broker” role in international conflicts and in disasters requiring significant and rapid humanitarian aid. …

The U.S. acknowledged all of this by establishing full diplomatic relations with the Holy See. A move to the U.S. Embassy to Italy would downgrade that relationship, as if the U.S.-Holy See relationship were a stepchild of U.S.-Italian relations. That is simply not true, for the range of issues on which America is engaged with the Holy See is broader, and in some respects more consequential, than the dialogue with our good ally, Italy.

To downgrade the U.S. Embassy to the Holy See is to ignore the ability of popes to put issues on the agenda of international conversation as no other leaders can. Moving Embassy-Vatican inside Embassy-Italy will not change that fact. But it will signal a lack of U.S. governmental respect for such papal influence, and it will not go unnoticed by other countries.