As Iraqi forces battle for control of the key cities of Fallujah and Ramadi in the Sunni-dominated Al Anbar province, many U.S. veterans of the fierce fighting in that area have watched with sadness, as their sacrifices and those of fallen brothers-in-arms appear to have been in vain. The news that al Qaeda fighters had seized at least partial control of both cities on Sunday has raised the question: Why is Iraq now descending into chaos?

President Obama's diehard defenders, predictably, blame George W. Bush, because they will never forgive "the decider" for invading Iraq in 2003. The U.S. response to the present events has been far more casual: expedited delivery of some missiles and surveillance drones, plus well-wishes to the Iraqi government for success against the terrorists. "This is a fight that belongs to the Iraqis. That is exactly what the president and the world decided some time ago when we left Iraq," Secretary of State John Kerry said during a visit to the Middle East on Sunday.

But why did the situation deteriorate so fast after U.S. troops left at the end of 2011? The answer: neglect. Obama came into office promising to end U.S. involvement in Iraq, and did not waver from that goal regardless of political and military changes there after November 2008.

Bush had acknowledged that he made mistakes in Iraq, and the surge, along with the outreach to Sunni tribes known as the Anbar Awakening, was his administration's response. Both initiatives set the stage for Sunni Arabs to participate in the 2010 national election after having boycotted the previous one. A coalition supported by many of them won the most seats, even though some of its candidates had been disqualified by an election commission headed by Ahmed Chalabi, a shadowy character initially thought to be a U.S. ally but later unmasked as an Iranian agent.

But unlike Bush, Obama dithered for months as Nouri al-Maliki, the Shiite prime minister re-elected in 2010, outmaneuvered his rivals and, with Iran's help, assumed office after months of internecine wrangling. Then, despite Maliki’s obvious intent to marginalize the Sunni Arab population, Obama headed for the exits.

After what was at best a half-hearted effort to negotiate an agreement to keep at least some U.S. troops in Iraq, Obama triumphantly — and repeatedly — declared the Iraq War over. But even then, the stage was set for al Qaeda's return among the embittered Sunnis.

Obama will neither admit to any mistakes, nor lift a finger to fix what he broke after taking office. And thousands of Iraqis – plus more of the credibility of the United States in the region — have died as a result. Here's hoping the events of the past week have finally taught the president two lessons: Wars don't end just because he says they're over. And people who depended upon and believed in America’s word die when a president leaves an important job unfinished.