The U.S quietly began withdrawing its military forces from Iraq on Sunday.

American soldiers at the Assad military base west of Baghdad were among the first to leave the country.

Their departure marked the first stage of President Obama's plan to have all American troops out of Iraq by Dec. 31.

There are concerns that the U.S. is withdrawing too soon as critics say the country isn't strong enough to protect itself.

Iraqi Prime Minister Nouri al-Maliki has said that his country's forces are ready to take over security after the U.S. pullout.

By January the remaining 39,000 troops in Iraq will be home, ending almost nine years of U.S. involvement in the Iraq War.

The war, which began in March of 2003, cost the lives of 4,400 American military personnel and more than $800 billion.