ROME – It’s probably fitting that the US withdrawal from Afghanistan, a 20-year, $2.6 trillion conflict that ended with the Taliban once again in power and America’s global standing in tatters, came more or less around the same time as today’s 20^th anniversary of the Twin Towers terrorist attacks of 9/11.

Two great US military campaigns were a direct result of the 9/11 attacks, in Afghanistan and Iraq, both of which have resulted either in failure or frustration. In both cases, Vatican diplomats today would be justified in saying, “Don’t say we didn’t tell you so.”

Afghanistan was the most immediate result of 9/11, an angry superpower’s effort to strike back at those it deemed responsible for the deadliest terrorist attack in human history.

From the beginning, the Bush administration made its intention clear to use force to dislodge the Taliban regime. Less than a month later, on Oct. 7, bombs and cruise missiles began to fall on Taliban targets, followed by ground troops 12 days later.

During the brief period after 9/11 but before the Afghan war opened, Pope John Paul II was one of the very few global leaders who made a trip to the region. The Polish pope was scheduled to travel to nearby Kazakhstan Sept. 22-25, and despite security fears after the Twin Towers attacks, the trip went ahead as planned.

It afforded John Paul a chance to weigh in on the fateful choices facing the world at that moment. In the immediate aftermath of the attacks, John Paul had denounced the “unspeakable horror” that unfolded in New York and dispatched a telegram to Bush to express “my profound sorrow and my closeness in prayer for the nation at this dark and tragic moment.” Now, however, circumstances called on John Paul to address not just the raw emotion but also the policy response.

He did just that. During his Angelus address after a Mass in the Kazakh capital of Astana on Sept. 23, the pope appended a special appeal, in English to make sure the international community heard it: “With all my heart, I beg God to keep the world in peace,” he said. In most media coverage, it was styled as a papal red light for the impending US-led military intervention.

Two months later, after the Taliban had been toppled and what amounted to two decades of foreign occupation had begun, John Paul made his warning even sharper in his annual message for the World Day of Peace.

In it, the pope acknowledged a right to defend oneself against terrorists but insisted that action should be limited to the terrorists themselves, not entire nations, and that any military or police action must be accompanied by “a courageous and resolute political, diplomatic and economic commitment to relieving situations of oppression and marginalization which facilitate the designs of terrorists.”

Though John Paul never mentioned the US specifically, in context the message seemed clear enough: No to indiscriminate uses of force, and no to a military campaign unmatched by an equally aggressive plan for rebuilding.

Two years later, the memory of the 9/11 attacks also fueled the US-led invasion of Iraq, which produced even more explicit condemnations from the pope and his Vatican team. John Paul even dispatched a special envoy to the White House, former Vatican ambassador to the US Cardinal Pio Laghi, in a last-minute bid to persuade the Bush administration to stand down, but to no avail.

In a nutshell, the pope and his diplomatic retinue warned the US that both Afghanistan and Iraq would prove to be open-ended conflicts that would likely leave the civilian population of both countries, including Iraq’s sizeable Christian minority, worse off. They also warned that attempts to impose Western models of government and justice on societies to whom those traditions are alien would never work, and that the specter of a Western power invading yet another Muslim nation would inflame Islamic sentiment and end up fueling the very jihadist movements the war was intended to curb.

In January 2003, during a working lunch with journalists hosted by Italy’s embassy to the Vatican, Italian Cardinal Angelo Sodano, then John Paul’s Secretary of State, put the assessment this way: “We say to our American friends: Is it in your interest to anger a billion Muslims and risk having the hostility of the Muslim world for decades?”

Just three days before the US invasion began, John Paul used his Sunday Angelus address to deliver another last-ditch appeal.

“In the face of the tremendous consequences that an international military operation would have for the population of Iraq and for the balance of the Middle East region, already sorely tried, and for the extremisms that could stem from it, I say to all: There is still time to negotiate; there is still room for peace, it is never too late to come to an understanding and to continue discussions,” he said.

While all that may seem obvious now, at the time the Vatican was one of the few Western states willing to be quite so public with its reservations about US policy. While it’s likely a fruitless exercise to ask how different the world might look today had John Paul found a hearing, the answer almost certainly has to be “a lot.”

Today’s twentieth milestone since 9/11, among many other things, offers a reminder that the Vatican had it right, not once but twice, about the heartache that would follow the military responses undertaken by the US and its allies in the wake of the attacks.

Perhaps that’s no more than grim consolation for Catholics on this awful anniversary. If nothing else, though, perhaps it also counsels a certain benefit of the doubt the next time Vatican diplomats attempt to warn the world, “That way madness lies.”

Follow John Allen on Twitter: @JohnLAllenJr