ROME – For anyone familiar with the Vatican’s recent history of bitter opposition to any US use of military force in the Middle East, Rome’s increasingly vocal support for the recent American airstrikes in Iraq may seem, to say the least, a little disorienting.

On Monday, the Vatican’s previously tacit approval for the American intervention turned explicit, as two senior officials offered what amounts to a blessing through official communications channels.

Archbishop Giorgio Lingua, the pope’s ambassador to Baghdad, told Vatican radio that the American strikes are “something that had to be done, otherwise [the Islamic State forces] could not be stopped.”

Lingua spoke plaintively of the ordeals faced by an estimated 100,000 Christian refugees from northern Iraq – many of whom, he said, are children – to account for his view of the American campaign.

“You can see these kids sleeping on the streets,” Lingua said, adding, “[there is so much] suffering.”

In a similar vein, Archbishop Silvano Tomasi, the Vatican’s envoy to the United Nations in Geneva, told Vatican Radio that “military action in this moment is probably necessary.”

Both Lingua and Tomasi went on to say that the international community needs to do more to unmask whoever’s supporting the radical Islamic State forces and to cut off its supply of arms, signaling reservations about widening the conflict.

At the same time, their endorsement of the American action, however grudging, was unmistakable. In light of recent history, it’s a sharp reversal of course.

In September 2013, when the Obama administration announced that it was weighing similarly limited air strikes against Syria in an effort to dislodge President Bashar al-Assad from power, the Vatican under Pope Francis unleashed a full-court diplomatic press against such a move, including Francis summoning all 1.2 billion Catholics in the world to a special day of prayer for peace on Sept. 7.

Further back in time, the late John Paul II and his diplomatic team moved heaven and earth to try to dissuade the Bush administration from unleashing its “shock and awe” campaign in Iraq in 2003, including the pontiff dispatching a special envoy and former ambassador to the United States, Italian Cardinal Pio Laghi, to try to convince the White House to back down.

John Paul continued to be an outspoken critic of that conflict, as he had been during the first US-led Gulf War under the first Bush administration in 1991.

Even after the Twin Towers attacks of Sept. 11, 2001, the Vatican was hardly univocal in terms of supporting an American incursion in Afghanistan. Aides to Pope John Paul II issued conflicting statements, with some appearing to express sympathy for striking at Taliban forces and others reservations.

Indeed, so strong was the Vatican’s anti-war push that one senior Vatican official said in a 2003 interview with the National Catholic Reporter that the Catholic Church was evolving towards an “abolitionist” stand on any unilateral use of force by a single state or an ad-hoc coalition.

Italian Cardinal Renato Martino, at the time the head of the Vatican’s Pontifical Council for Justice and Peace, said in 2003 that going forward the only “humanitarian intervention” the Vatican was likely to approve was an international peace-keeping exercise specifically authorized by the United Nations or some other planetary authority.

So, what gives? What’s the significance of the Vatican offering the Obama administration this time around, if not a green light, certainly a clear yellow?

Three points seem most important.

First, there seems a small but telling shift in Vatican reflection on what constitutes a “just war.” Martino’s 2003 comment suggested that the leadership of the Catholic Church was only prepared to endorse a military incursion, however well-motivated, if it came with explicit international authorization, which in practice means the blessing of the United Nations.

The face-value way to read Monday’s comments from Lingua and Tomasi, however, is as a recognition that there are times when the situation is sufficiently urgent that anyone who steps in, with or without a formal U.N. resolution, can claim the moral high ground.

Even if full legitimacy under international law remains the ideal, in other words, there’s now an exception on the record in favor of “unilateral” action.

Second, the emerging Vatican line clearly establishes a limit to pacifism as an option within Catholic social teaching. In effect, the take-away is that there are times when the use of force is the only option left to serve the greater good.

Third, and most basically, what’s different about 2014 with respect to 2003 isn’t so much the theory but the facts on the ground.

One core reason the Vatican opposed the two Gulf Wars, as well as any expansion of the conflict in Syria, was fear that the fall of a police state in the Middle East would lead to the rise of a radical Islamic theocracy in which Christians and other minorities would find themselves in the firing line.

That’s no longer a theoretical anxiety. It’s the lived reality of the new caliphate proclaimed by the Islamic State, which means that the Vatican and other Christian leaders are no longer so worried about the aftermath of a conflict. They’re much more preoccupied by the here and now, and thus more inclined to back anyone who seems prepared to do something about it.

No doubt Pope Francis and other Catholic leaders will issue calls for peace and dialogue in the days ahead, including the special envoy Francis just dispatched to Iraq, Italian Cardinal Fernando Filoni, a former papal ambassador in the country (and, for the record, a leading critic of the US-led invasion in 2003).

What’s going on at the moment, however, would seem to be a de facto recognition that there are times – however rare, and however lamentable – when “give peace a chance” may work as a fervorino, but as foreign policy it doesn’t quite do the trick.