Can Pope Leo remain a US citizen now that he's a foreign head of state?

Pope Leo XIV's election as the first U.S.-born leader of the Catholic Church elevated him to the extremely rare, and legally thorny, position of being an American citizen who now is also a foreign head of state.

Born in Chicago as Robert Prevost in 1955, the new pope for the past decade has held dual citizenship in the U.S. and Peru, where he spent time as a missionary and bishop.

As pope, Leo serves as leader of both the Holy See, the governing body of the Catholic Church, and Vatican City, an independent state.

Can the pope remain a U.S. citizen while leading a foreign government? Here are things to know about Leo's citizenship.

Is the Vatican considered a sovereign nation? In addition to being the spiritual leader for what the church says is roughly 1.4 billion Catholics worldwide, Leo is also the head of what's recognized as the world's smallest nation.

Vatican City covers just 0.17 square miles (0.44 square kilometers) and has a population of a few hundred people. It became an independent state in 1929 under a treaty between Italy and the Holy See.

Could Leo be stripped of his U.S. citizenship? Americans working for foreign governments aren't automatically at risk of forfeiting their U.S. citizenship.

But the U.S. State Department says on its website that it may "actively review" the citizenship status of Americans who "serve as a foreign head of state, foreign head of government, or foreign minister."

"Such cases raise complex questions of international law, including issues related to the level of immunity from U.S. jurisdiction that the person so serving may be afforded," the policy states.

The State Department declined to comment on the pope's status. A spokesperson said the department doesn't discuss the citizenship of individuals.

The core issue is whether foreign leaders should hold American citizenship when they also enjoy broad immunity from U.S. laws, said Peter Spiro, a Temple University law professor and an expert on citizenship law. Such immunity clashes with the constitutional principle that no U.S. citizen should be above the law.

However, the U.S. Supreme Court in a 1980 decision ruled that Americans can't be stripped of their citizenship unless they intentionally renounce it.

"The State Department never assumes that you intend to lose your citizenship unless you specifically say so through the renunciation process," Spiro said.

He said it would be hard to argue that Leo, by becoming pope, demonstrated an intent to give up being a U.S. citizen.

"I think it's highly unlikely that the U.S. moves to terminate the pope's citizenship," Spiro said.

Can the pope remain a citizen of Peru? Peruvian law has no conflict with Pope Leo remaining a citizen, said Jorge Puch, deputy director of registry archives at Peru's National Registry of Identification and Civil Status.

Leo was granted Peruvian citizenship in August 2015, the month before Pope Francis appointed him bishop of Chiclayo in the South American country's northern region. To qualify, he had to live in Peru for at least two years and pass a civics test.

"It is the most praiseworthy thing our beloved supreme pontiff could have done: Wanting to have Peruvian nationality without having been Peruvian by birth," Puch said.

All adult Peruvians, including naturalized citizens, are required to vote in elections through age 69. Voting in Peru's presidential election next April won't be mandatory for Leo. He turns 70 in September.

Did prior popes retain citizenship in their home countries? It's not clear what happened to the citizenship status of Leo's predecessors once they became pope. That's not information the Vatican discloses.

Pope Francis renewed his passport in his home country of Argentina in 2014, the year after he became pope. German-born Pope Benedict XVI and Pope John Paul II, a native of Poland, never publicly relinquished citizenship in their home countries.

John Paul was the first non-Italian pope in 455 years.

Margaret Susan Thompson, a Syracuse University history professor and expert on American Catholicism, said she doubts Leo would renounce his U.S. citizenship. But she believes the new pope was sending a message when he delivered his first speech in Italian and Spanish without using English.

"I think he wants to stress that he is the pope of the universal Catholic Church," Thompson said, "and not an American holding that position."

Have other US citizens served as leaders of a foreign government? Yes. Here are a few notable examples.

Former British Prime Minister Boris Johnson was born in New York to British parents in 1964. He left the U.S. as a young boy and renounced his American citizenship in 2016 while serving as the U.K.'s foreign secretary. Johnson became prime minister three years later.

Mohamed Abdullahi Mohamed was an American citizen when he was elected president of Somalia in 2017. Born in Somalia, he moved to the U.S. in 1985 and became a citizen in the 1990s. Mohamed gave up his U.S. citizenship two years into his presidency.

Valdas Adamkus became a U.S. citizen after his family fled Lithuania to escape Soviet occupation. He returned to win Lithuania's presidency in 1998, years after the Soviet Union collapsed. He relinquished his American citizenship after being elected.