A South Oil Company employee looks on as smoke rises following a pipeline explosion south of Basra in al Faw, Iraq, in March 2004 | EPA/SHAWN BALDWIN Opinion The George W. Bush refugees As migrants pour into Europe, Americans must bear the blame.

‘‘If you break it, you own it.” Colin Powell’s Pottery Barn Rule, warning George W. Bush of the consequences of invading Iraq, turned out to be dead wrong.

Make that half wrong. Bush broke it — “it” being a swath of the greater Middle East. But the U.S. adamantly refuses to accept anything like ownership of the consequences stemming from Bush’s recklessly misguided act.

Not least among those consequences is the crisis that finds refugees fleeing Syria, Iraq, Afghanistan and other parts of the Islamic world in search of asylum in the West. The European nations most directly affected have greeted this wave with more hostility than hospitality — Germany, for a time, at least offering a notable exception.

For its part, the U.S. has responded with pronounced indifference. In a gesture of undisguised tokenism, the Obama administration has announced it will admit a grand total of 10,000 Syrians — one-eightieth the number that Germany has agreed to accept this year alone.

No doubt proximity plays a part in explaining the contrast between German and U.S. attitudes. Viewed from Wichita or Walla Walla, the plight of those who hand themselves over to human traffickers in hopes of crossing the Mediterranean plays out at a great distance. Syria is what Neville Chamberlain would have described as a faraway country of which Americans know nothing (and care less). And Iraq and Afghanistan are faraway countries that most Americans have come to regret knowing.

Such attitudes may be understandable. They are also unconscionable.

* * *

To attribute the refugee crisis to any single cause would be misleading. A laundry list has contributed: historical and sectarian divisions within the region; the legacy of European colonialism; the absence of anything even approximating enlightened local leadership able to satisfy the aspirations of people tired of corruption, economic stagnation, and authoritarian rule; the appeal — inexplicable to Westerners — of violent Islamic radicalism. All play a role.

Yet when it comes to why this fragile structure collapsed just now we can point to a single explanation — the cascading after-effects of a decision made by Bush during the spring of 2002 to embrace a doctrine of preventative war.

The previous autumn, U.S. forces toppled the government of Afghanistan, punishing the Taliban for giving sanctuary to those who plotted the 9/11 attacks. Bush effectively abandoned Afghanistan to its fate and set out to topple another regime, one that had no involvement whatsoever in 9/11.

For Bush, going after Saddam Hussein’s Iraq formed part of a larger strategy. He and his lieutenants fancied that destroying the old order in the greater Middle East would position the U.S. to create a more amenable new order. Back in 1991, after a previous Iraq encounter, Bush’s father had glimpsed a “new world order.” Now a decade later, the son set out to transform the father’s vision into reality.

The administration called this its Freedom Agenda, which would begin in Iraq but find further application throughout the greater Middle East. Coercion rather than persuasion held the key to its implementation, its plausibility resting on unstoppable military power. For Bush’s inner circle, including Dick Cheney, Condoleezza Rice, Donald Rumsfeld and Paul Wolfowitz (but not Powell), victory was foreordained.

They miscalculated. The unsettled (but largely ignored) condition of Afghanistan after the fall of the Taliban already hinted at the extent of that miscalculation. The chaos that descended upon Iraq as a direct result of the U.S. invasion affirmed it. The Freedom Agenda made it as far as Baghdad and there it died.

That Saddam was a brutal tyrant is a given. We need not mourn his departure. Yet while he ruled he at least kept a lid on things. Bush blew off that lid, naively expecting liberal democracy or at least deference to American authority to emerge. Instead, “liberating” Iraq produced conditions conducive to the violent radicalism today threatening to envelop the region.

The Islamic State offers but one manifestation of this phenomenon. Were it not for Bush’s invasion of Iraq, ISIL would not exist — that’s a fact. Responsibility for precipitating the rise of this vile movement rests squarely with Washington.

So rather than cluck over the reluctance of Greeks, Serbs, Hungarians and others to open their borders to those fleeing from the mess the U.S. played such a large part in creating, Americans would do better to engage in acts of contrition.

On the 10th anniversary of Hurricane Katrina, former president Bush visited New Orleans, implicitly acknowledging that his administration’s response to that disaster just might have fallen a bit short. It was a handsome gesture. A similar gesture is in order toward the masses fleeing the region he set out to remake.

It’s never too late to say you’re sorry.

Andrew Bacevich’s new book “America’s War for the Greater Middle East: A Military History” is due out next year.