Pope Leo XIV's diplomatic efforts may impact U.S. foreign policy, analyst says

WASHINGTON (OSV News) — In a little over a month since his election to the papacy, Pope Leo XIV has appeared to embrace his role as a head of state to promote Catholic principles about peacebuilding, an analyst told OSV News. His actions as a head of state could also impact U.S. diplomacy.

Among the first actions of his pontificate, Pope Leo offered the Vatican as a host for talks to end Russia’s invasion of Ukraine and called for a ceasefire in Gaza, further urging humanitarian aid to reach its residents.

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News that “times of transition such as this — for the church, for states, for technology — offer both risk and opportunity.”

Pope Leo XIV speaks to diplomats during an audience with the Vatican diplomatic corps in the Apostolic Palace’s Clementine Hall at the Vatican May 16, 2025. (CNS photo/Vatican Media)

“Past assumptions no longer persuade, so new moral and legal solutions can be found,” O’Connell said. “It is a time fraught with both possibility and risk. The first weeks of Leo’s pontificate indicate reason for optimism. His offer of the Vatican to Russia and Ukraine as a venue for peace talks was inspired and inspiring.”

The late Pope Francis, O’Connell said, “was one of the church’s greatest popes for peace.”

“He took the name of a saint associated with peace and the poor,” she said, “He worked tirelessly to end conflicts that drive the other ills of the earth, including forced migration, disease, poverty, and environmental devastation. He helped support peace agreements in South Sudan and Colombia.”

The late pontiff also “denounced nuclear weapons and the immoral theory that urges nations to possess them — mutually assured destruction,” O’Connell said, pointing to a 2017 address by Pope Francis at a Vatican conference.

“Pope Francis’s final Easter prayers sought peace in Ukraine, Gaza, Yemen, Myanmar and Congo,” she added. “From Pope Leo XIV’s first weeks in office it is clear that he will continue Pope Francis’s commitment to peace. The call to be a peacemaker is his and ours directly from Christ.”

The first U.S.-born pontiff will also have to navigate a relationship with President Donald Trump and Vice President JD Vance — the second Catholic to hold that role — as their approaches to issues such as climate and immigration policy, as well as conflict resolution in places like Gaza and Ukraine, might differ.

Trump, who as a candidate repeatedly said that he would be able to end the war between Russia and Ukraine “in 24 hours” upon taking office, reached his fifth month in office without having secured a resolution. U.S. officials, including Trump, have expressed interest in the Vatican hosting such talks.

“Pope Leo will face challenges as Pope Francis did and beyond,” O’Connell said. “In addition to the problem of war, the church itself has many needs and major problems. Pope Leo will need to use resources wisely — including his own time. He can rely on Catholic academics and thinkers, but needs to find the women and men who are truly proficient in the art of diplomacy and have knowledge of authentic international law.”

In remarks to papal diplomats June 10, Pope Leo told them, “I count on you so that everyone in the countries where you live may know that the church is always ready for everything out of love, that she is always on the side of the least, the poor and that she will always defend the sacrosanct right to believe in God, to believe that this life is not at the mercy of the powers of this world, but is permeated by a mysterious meaning.”