(ABCNews)-- The crack of gunfire shattered the quiet following afternoon prayers in Fallujah on Thursday, an Iraqi city that U.S. forces once wrested from al Qaeda-linked forces in fierce and bloody fighting and is now a fresh battleground for the terror group.
Inside the ancient city, just 43 miles from Baghdad, Iraqis are once again braced for a siege and say security has declined precipitously over the past year. On Thursday, Iraqi interior ministry officials declared that half of the city was occupied by a brutal wing of al Qaeda called the Islamic State of Iraq and the Levant.
What little peace this city has seen in the past decade came at the expense of dozens of American Marines who fought al Qaeda-backed insurgents in two battles in 2004. They finally eliminated the al Qaeda forces in a house by house, alleyway by alleyway battle in which Marines had to contend with booby traps, roadside bombs and insurgents who fought with near suicidal determination.
"No one expected the level of ferocity we encountered in Fallujah," said Maj. Charleston Malkemus, a member of the Marines' First Batallion, the first division deployed to the city. "Insurgents and al Qaeda fighters flocked to the city and inserted themselves to take control, similar to what's going on now."
The second battle of Fallujah fought in the final months of 2004 was the greatest urban military operation involving U.S. troops since the battle for Hue City, Vietnam, in 1968.
By one estimate 36,000 of the city's 50,000 homes in Fallujah were laid to waste. More than 2,000 insurgents are believed to have been killed in the fighting, as were nearly 100 American troops.
Al Qaeda was routed from the city, but they have returned in force according to officials, leaving some Americans to wonder whether too many died in vain.
"It was all for naught," said Ross Ducati, a former Marine who fought in the second battle for the city and has since become an outspoken critic of U.S. intervention in Iraq. "Americans fought and died there -- my friends died there -- for the purposes of regime change and furthering business interests friendly to the Bush administration… [Now] Iraqis will die there to further the interests of [Prime Minister Nouri] al-Maliki's government."
But other Marines don't share that view, seeing the latest confrontation with al Qaeda as part of an ongoing struggle for freedom in Iraq and across the region.
"We can't sustain fighting from 3,000 miles away forever," said Malkemus. "At some point we had to turn things over to the Iraqis. Unfortunately, the Iraqi Army is struggling and needs to engage with the terrorists again in Fallujah.
"American men and women who fought and died can never be forsaken, and we don't forsake them by keeping up the fight," he said.
The security situation in Iraq has deteriorated in the past year. According to the U.N., 7,818 people were killed in 2013, the highest number in years.
Much of the recent sectarian violence has taken place in Anbar province, where Fallujah is located. Prime Minister Maliki's Shiite-controlled government has tried to contain the violence in the province, a majority Sunni region.
Against the backdrop of al Qaeda backed militias launching attacks on police statements and military bases, the government has also cracked down on peaceful Sunni protests and sit-ins and dismantled Sunni militias, including those unaffiliated with al Qaeda.