In April, reflecting on his role in the 2003 invasion of Iraq, former British Prime Minister Tony Blair claimed that the Arab Spring which tore a number of Middle East nations apart in 2011-2012 would have also destabilized Iraq if Saddam Hussein been left in power. “You would be facing what you’re facing in Syria now in Iraq,” Blair claimed. That self-congratulatory proclamation seems premature today.

The Islamic State in Iraq and Syria (ISIS) is busy opening up old wounds for Americans who committed blood and treasure to that country’s transition from Hussein’s rule. On Tuesday, ISIS insurgents overran Iraqi defenders in the city of Mosul. On Wednesday, Tikrit, Hussein’s home town, fell to ISIS fighters. Baghdad, where as some reports indicate ISIS already maintains operational capacity, stands just 180 kilometers away.

This map, via the Institute for the Study of War, illustrates ISIS’s borderless theater of operations which stretches from Al-Bab in Syria to Hillah in Iraq.

“The group looks at Syria and Iraq as one interchangeable battlefield, and its ability to shift resources and personnel across the border has measurably strengthened its position in both theaters,” an American counterterrorism official told The Washington Post.

According to Michael Vickers, the undersecretary of defense for intelligence, the ISIS represents a reconstitution of al-Qaeda in Iraq. “Most of the leadership went to Syria after being significantly degraded in Iraq,” Vickers recently told a Center for Strategic and International Studies conference.

The Post’s story on the rise of ISIS is troubling for a variety of reasons, not the least of which is the indication that the United States may be signaling that the time for containing this threat to regional stability has past.

“Washington will be questioning how to move forward in terms of supporting the Iraqi army,” [Iraq specialist at the Brookings Doha Center. Charles] Lister said. “Every time ISIS captures territory, it’s a reminder that it does so using weapons that have fallen into the hands of the forces the U.S. is trying to counter in the first place.”

This video, featuring an ISIS fighter holding an American rifle and standing in front of a seized Iraqi APC seems to confirm that:

It is possible that the gruesome and precedent-setting Syrian conflict might have been contained within its borders had the Western world acted in 2013, when the political pressure to do so was at its greatest.

A Washington Institute analysis from the summer of 2013, which warned of an impending governmental collapse in Syria and how to prevent it, proposed an option for limited Western intervention with the aim of preventing it spilling over into Lebanon, Jordan, Turkey, and Iraq. “[T]he United States,” the report advised, “should establish 50- to 80-mile-deep safe areas within Syria along its borders with Jordan and Turkey.”

Critics of intervention often cast the idea of creating a no-fly zone in Syria as too risky for the U.S. pilots and planes that would be involved. But a limited approach focused on border regions would be less perilous, since the regime’s planes and missiles could be shot down using Patriot missile batteries based in Jordan and Turkey or by aircraft flying there. And the safe areas would still allow civilians to take shelter from Assad’s onslaught, keep refugees from flooding into neighboring countries, and enable the international community to funnel in humanitarian aid on a scale that local nongovernmental organizations cannot match.

The report also warned, as others did, of the desire of some anti-Assad fighters to spread the conflict across Syria’s borders in order to erode the Syrian leader’s support structure.

“The main reason such groups have come to play such a big role in the opposition is that the anti-Assad forces have had to turn to the Gulf states for weapons and money — and the sources there have favored the Salafists, which according to some estimates account for up to a quarter of all the opposition fighters,” the report continued. ”The United States could earn the influence it seeks by providing intelligence, military training, and weapons of its own.”

To describe the eventual recipients of advanced American weaponry as unsavory would be an understatement. But the threat to regional stability is so great that those concerns were apparently discarded earlier this year. The United States and Saudi Arabia began a pilot program to supply Syrian revels with sophisticated weaponry for the first time in April, but the move came only after months of fruitless diplomatic efforts to freeze the Syrian conflict. It is, in all likelihood, too little, too late.

As the names of cities within the Sunni Triangle that were seared into the American consciousness in the last decade come to dominate the headlines again, it is worth asking if this dangerous and humiliating development could have been prevented. Had the political will to act been present in 2013, it’s entirely possible that it could have been.