End of Iraq war: US ends mission with ceremony in Baghdad

American forces on Thursday lowered the US flag in Iraq, as the last troops are withdrawn after nearly nine years of war, Agence France Press reported.

Defense Secretary Leon Panetta attended the formal ceremony to mark the end of the US military campaign in Iraq – and the closure of the military's headquarters in Baghdad.

More on GlobalPost: President Obama marks end of Iraq war at Fort Bragg

According to a report in The New York Times, Panetta told the crowd:

Let me be clear: Iraq will be tested in the days ahead — by terrorism, and by those who would seek to divide, by economic and social issues, by the demands of democracy itself… Challenges remain, but the US will be there to stand by the Iraqi people as they navigate those challenges to build a stronger and more prosperous nation.

President Barack Obama on Wednesday marked the end of the US operation in Iraq, by praising what he called the "extraordinary achievement" of American troops, CNN reported.

In a speech to recently returned soldiers at Fort Bragg, North Carolina, Obama said nearly 4,500 Americans had died in the Iraq war.

"As your commander in chief, and on behalf of a grateful nation, I'm proud to finally say these two words, and I know your families agree, welcome home. Welcome home … Because you sacrificed so much for a people that you had never met, Iraqis have a chance to forge their own destiny."

Most of the last remaining US soldiers are expected to withdraw from Iraq within days.

Obama used his speech, which was received with cheering and applause, to mark the fulfillment of a campaign pledge he made in 2008 to end the war on Iraq, CNN reported.

Most of the remaining 5,500 soldiers have now left Iraq, leaving the country’s security in the hands of the Iraqi authorities, the BBC reported, adding that the US was to be lowered in the capital, Baghdad.

Read more at GlobalPost: 8,000 US troops left in Iraq, down to zero by end of year

Obama said the US was leaving behind a "sovereign, stable and self-reliant Iraq."

He also acknowledged the financial struggle of American military families throughout the war, saying they had the thanks of “a grateful nation."

The military campaign itself cost the United States an estimated $1 trillion.

Republicans have criticized the troop withdrawal, arguing that some forces should ensure Iraq's security.