The stunning conquest of Fallujah and Ramadi by al Qaeda fighters has reignited the debate about whether the White House should have left combat troops in Iraq. But that argument obscures what may be the original sin of the U.S. withdrawal from Iraq two years ago: Washington’s refusal to provide Baghdad with the F-16s and Apache attack helicopters that could turn the tide in the bloody fight to recapture the key cities.

The Iraqi military has surrounded Fallujah with ground troops and armored vehicles, and Iraqi Prime Minister Nouri al-Maliki indicated Monday that he was prepared to order an all-out assault on the city if tribal fighters there failed to expel the al Qaeda fighters on their own. In a jab at the White House, a senior Iranian military official, Gen. Mohammad Hejazi, said Tehran was prepared to give Baghdad weaponry and military trainers to help in what could be weeks of grinding house-to-house, street-to-street fighting.

Current and former U.S. officials say that F-16s and Apaches would change the situation on the ground by giving Iraqi commanders the ability to destroy al-Qaeda targets from the air and prevent reinforcements from reaching the cities. Baghdad has spent years pressing Congress and the White House for permission to buy dozens of the aircraft. So far, though, Washington has said no. […]