When the newly elected Leo XIV stepped onto the loggia of St Peters’ Basilica in May 2025 with “Peace be with you,”, it sounded less like a slogan than a brief for the diplomats. Part 2 of this series breaks Vatican diplomacy down into five core principles and shows it applied in two cases: Cuba, where quiet facilitation helped unlock a stalemate, and Ukraine, where it hits hard limits
As Pius XII once put it, “Nothing is lost with peace; everything can be lost with war” – and that is the thread running through the five principles that structure Vatican diplomacy.
The Method: Five Principles of Holy See Diplomacy
The first principle, Moral Authority and Mission, frames diplomacy as a moral task grounded in Catholic Social Teaching: it argues for universally valid values (dignity, solidarity, peace), claiming a moral approach as a “key actor of global governance”. The Holy See has used that language at UN ECOSOC, calling support for crisis-hit developing countries a “moral obligation,” pointing to debt, weak growth, and food insecurity.
The second principle, Commitment to Peace, is the cornerstone: Vatican influence is mostly soft power, aiming to persuade rather than coerce. Its recurring priorities follow from that — peacebuilding, protection of fundamental rights and defence of human dignity —, summarised as fighting spiritual/material poverty, building peace, and acting as a bridge-builder.
In the absence of territorial ambitions and one single electorate, the Holy See is less tied to domestic pressures and can credibly avoid partisan alignment, a stance stipulating the third principle of Non-Statehood and Impartiality.
Equidistance as fourth principle — keeping channels open to all sides — is crucial for mediation, which is why the Holy See avoids neutrality-compromising alliances. This can be delicate: the Latin Patriarch of Jerusalem, Cardinal Pizzaballa, warned in April 2024 against treating the middle east conflict like a “soccer derby,” while the Holy See called for a ceasefire, release of hostages, and humanitarian access. His warning about “false neutrality” captures the balance: remain present to suffering without being absorbed into political-military camps.
The fifth principle of Engagement with International Platforms and the “Duty to Politics” means that the Holy See works through multilateral fora, especially the UN, to push peace and moral claims into global debates. Its engagement is openly political — on disarmament, migration, climate — grounded in a Christian view of the person: transcendent dignity implies a “duty toward politics”.
Cuba as Proof of Concept
In the U.S.–Cuba thaw beginning in 2014, secret talks were underway, including discussions about prisoner exchanges, but they stalled. At that point the Holy See entered as credible “honest broker”. President Barack Obama publicly credited Pope Francis’ personal appeal and facilitation — indicating that the papacy could lend legitimacy to a shift that would otherwise look politically risky.
Francis delegated the task, showing another Vatican instinct: mediation is often most effective when it is local, informed, and discreet. Cardinal Jaime Ortega, then-Archbishop of Havana, became the connecting figure. The result was a deal finalized after a Vatican-hosted round of talks in October 2014 and a significant wave of international approval.
Cuba shows what Vatican diplomacy can do when channels exist, parties want a way out, and an inconspicuous intermediary can help them cross the final meters.
Ukraine as the Limit Case
Ukraine is the harder test — not because the Holy See lacks attention, but because the conflict’s political logic is far less permissive. Vatican diplomacy has followed its familiar pattern, often in three layers.
First, classic diplomacy: keep official dialogue open, including with Russia, and insist on humanitarian issues as a shared minimum. The Holy See’s Secretary for Relations with States and IO’s visit to Ukraine in May 2022 added an important corrective to the caricature of “neutrality”: he publicly reaffirmed Ukraine’s territorial integrity and sovereignty, anchoring Vatican engagement in basic international-law language.
Second, personal papal diplomacy: gestures that states rarely make because they look odd in protocol terms. Francis visited the Russian embassy to the Holy See early on — an unusual move meant to signal urgency and personal investment.
Third, humanitarian lanes: the space where Vatican method is most viable when the political track is blocked. The Church’s network — Caritas, local parishes, Catholic organisations — becomes part of the diplomatic ecosystem. Cardinal Zuppi’s 2023 missions to Kyiv and Moscow focused on concrete humanitarian files: prisoner exchanges and the return of Ukrainian children taken to Russia. The Secretary of State’s visit to Ukraine in 2024 reinforced that idea: even when a comprehensive deal is unrealistic, small humanitarian steps are worth fighting for.
Ukraine shows the ceiling as well as the value. If Cuba showed what Vatican diplomacy can make possible, Ukraine shows where its limits begin. Even so, the Holy See can keep channels alive and defend humanitarian space in a deeply polarised conflict. Part 3 turns to what this means in the current moment, as Pope Leo gives Vatican diplomacy a more defined tone.
