ROME – As several western nations, including the United States, have given Ukraine approval to use their weapons in strikes on Russian territory, the Vatican’s top diplomat has warned that such moves would mark a serious escalation in the Ukraine war and represent a “disturbing” prospect.

Speaking to journalists on the margins of a book presentation in Milan this week, Italian Cardinal Piero Parolin, the Vatican’s Secretary of State, said of the use of NATO weaponry against Russia, “I think it should concern every person that cares about the fate of our world.”

“It could lead to an escalation that no one will be able to control, it is a disturbing prospect,” he said.

Parolin was in Milan for the presentation of a book titled, “At the service of Italy and the Pope,” about Italian banker Bernardino Nogara, founder of the so-called “Vatican Bank,” the formal title of which is the Institute for the Works of Religion.

Parolin’s remarks came as members of the North Atlantic Treaty Organization (NATO) are considering authorizing Ukraine to use weapons they have provided on targets in Russian territory.

Discussion on this point has increased in recent days after Russia launched a new offensive in Kharkiv, the latest of its efforts to make advancements in Ukraine after initiating a full-scale invasion in February 2022.

NATO Secretary General Jens Stoltenberg has urged members of the alliance to lift restrictions on the use of military support provided to Ukraine, allowing Kyiv to strike “legitimate military targets” inside of Russia.

Similarly, British Foreign Secretary David Cameron in early May said Ukraine could use weapons provided by London on targets inside of Russia, and that it was up to Kyiv to decide whether to do so.

On Tuesday French President Emmanuel Macron during a 5-day visit to Germany said, “we should allow them to neutralize military sites from which missiles are fired, military sites from which Ukraine is attacked.”

German Chancellor Olaf Scholz, who was present at a joint press conference with Macron, backed this position, which has also been supported by several Eastern European members of NATO.

United States President Joe Biden Thursday partially lifted restrictions on how Ukraine can use military supplies sent by the US, indicating a partial step toward using American weapons inside Russia.

In response, senior Russian security official Dmitry Medvedev warned that it was ready to strike back if western weapons were used, saying, “Russia regards all long-range weapons used by Ukraine as already being directly controlled by servicemen from NATO countries.”

“This is no military assistance, this is participation in a war against us,” he said, saying, “such actions could well become a casus belli,” meaning an act that provokes a war.

Medvedev said it would be a “fatal mistake” for the West to think that Russia was not ready to use tactical nuclear weapons against Ukraine, and alluded to the strike of unnamed hostile countries with strategic nuclear weapons, “This is, alas, neither intimidation nor bluffing.”

In terms of the Holy See’s own intervention in the Ukraine war, Parolin said “we are involved at the humanitarian level, above all on the issue of the return of Ukrainian children to their homeland.”

Collaboration on this front began with Cardinal Matteo Zuppi of Bologna’s visit to Moscow last summer as Pope Francis’s official peace envoy for the Ukraine war, he said, saying Zuppi’s mission “continues not in a very rapid manner, but it is bearing fruit.”

In his role as the Ukraine peace envoy, Zuppi has made visits to Moscow, Kyiv, Washington DC and Beijing, mostly advancing a humanitarian agenda. The Vatican multiple times has offered to mediate the conflict, however, Ukrainian authorities have insisted that they are not in need of mediation, and that any peace plan for ending the war must be on their terms.

Parolin also urged participation in this month’s EU parliamentary elections, saying the Church “is never party-oriented” and as such, “we cannot express ourselves in favor or against one or the other.”

However, he stressed the importance of European citizens participating in the vote, “because this means implementing and exercising democracy.”

At the same time, Parolin, echoing the concerns of many of Europe’s bishops, said citizens must also “take into account the values of the candidates who are close to, similar to, Catholic sensitivity. I would say that these are the principles we should adhere to as far as we are concerned.”

Follow Elise Ann Allen on X: @eliseannallen