( CNN ) -- The U.S. general who oversaw the withdrawal of American troops from Iraq returned home Tuesday with the flag that flew over Baghdad at the end of the war . President Barack Obama and Vice President Joe Biden joined military leaders at the military 's Joint Base Andrews outside Washington as Army Gen. Lloyd J. Austin III returned the United States Forces-Iraq command flag . The ceremony marks the formal conclusion of the conflict . `` Today , we bring home the colors to United States soil , '' the chairman of the Joint Chiefs of Staff , Gen. Martin Dempsey , said during Tuesday 's commemoration . `` At the same time , we embrace many of our own back into the fold just in time for the holidays . Welcome home . '' Neither Obama nor Biden spoke at Tuesday 's ceremony . The last U.S. convoy left Iraq early Sunday , bringing an end to a nearly nine-year war that sharply divided the U.S. public . Nearly 4,500 U.S. troops died and more than 30,000 were wounded in the conflict , while estimates of the Iraqi toll run well above 100,000 dead . `` We lack the words to say what you feel on this day because , try as we may , we can never fully know it , '' Deputy Defense Secretary Ashton Carter told the families of those killed or wounded . `` But we do know what your sacrifice means to us , to this nation and to a world that still depends so much on America for its security . '' The standard that Austin presented in Tuesday 's ceremony was the flag that was sheathed last week in a formal `` casing of the colors '' in Baghdad . He said U.S. troops , many of whom served multiple tours in Iraq , have achieved `` truly remarkable '' things . `` Together with our coalition partners and corps of dedicated civilians , they removed a brutal dictator and gave the Iraqi people their freedom , '' Austin said . `` Their courage and their ability to adapt has enabled us to persevere through the darkest days of the insurgency , to create hope and to provide the Iraqis opportunities that they have not seen in their lifetime . And so now the stage has been set for Iraq 's young democracy to emerge as a leader in what has been and what will continue to be a very dynamic region . '' U.S. and allied troops , mostly British , invaded Iraq in March 2003 after accusing then-dictator Saddam Hussein of concealing banned stockpiles of chemical and biological weapons and efforts to build a nuclear bomb . Hussein 's government quickly collapsed , but U.S. inspectors later found that Iraq had dismantled its weapons programs under U.N. sanctions in the 1990s . The U.S. occupation quickly found itself battling an insurgency launched by the remnants of Hussein 's regime . The Americans also faced Islamic jihadists loyal to an Iraq-based offshoot of al Qaeda and anti-American Shiite militias that U.S. commanders said were backed by neighboring Iran . Iraq elected a new government in 2005 , and Hussein was hanged in 2006 . But soon afterward , sectarian warfare between Iraq 's Shiite Arab majority and Sunni minority erupted after the bombing of the Shiite al-Askariya mosque , with thousands of bodies dumped in the streets of Baghdad and other cities for months . That fighting subsided in 2007 , after Washington poured about 30,000 more troops into Iraq and began supporting Sunni Arab groups that turned against the jihadists . The new Iraq finds itself facing a political crisis within days of the American pullout , as Prime Minister Nuri al-Maliki 's Shiite-dominated government accused the country 's leading Sunni official of orchestrating bomb attacks against government and security officials . The powerful political bloc that draws support largely from Sunni and more secular Iraqis has announced it is boycotting Parliament , and its leaders accuse al-Maliki of trying to amass dictatorial power . CNN 's Dan Merica contributed to this report .
NEW : U.S. troops did `` truly remarkable '' things in Iraq , Austin says . `` Welcome home , '' Joint Chiefs chairman tells troops . Tuesday 's ceremony was the formal finale of the U.S. military mission in Iraq . As many as 4,500 Americans were killed in the nearly 9-year war .