Susan Walsh/AP Photo

ABC News’ Jake Tapper and Huma Khan report:

President Obama today announced that the United States will pull all its troop from Iraq by the end of the year, as ABC News first reported.

“Today, I can report that as promised, the rest of our troops in Iraq will come home by the end of the year,” the president said. “After nine years, America’s war in Iraq will be over.”

Obama vowed to work with the Iraqi government in the coming years, and said the two were “in full agreement about how to move forward.”

On a broader scale, the president stressed that “the end of war in Iraq reflects a larger transition.”

“The tide of war is receding,” he said of the war that started under President George W. Bush in 2003.

About 4,000-5,000 security contractors will remain in Iraq, the White House said.

The Status of Forces Agreement between the United States and Iraq expires at the end of the year. Officials had been discussing the possibility of maintaining several thousand U.S. troops to train Iraqi security forces, and the Iraqis wanted troops to stay but would not give them immunity, a key demand of the administration.

“This deal was cut by the Bush administration, the agreement was always that at end of the year we would leave, but the Iraqis wanted additional troops to stay,” an administration official said. “We said here are the conditions, including immunities. But the Iraqis because of a variety of reasons wanted the troops and didn’t want to give immunity.”

Deputy National Security Adviser Denis McDonough told reporters that the U.S. assessment determined that Iraqis were ready and they proved they could fully take over their security. The U.S. will have a robust diplomatic presence and continue to train Iraqi forces, he said, but it will be similar to what it has in other countries.

“We’re going to have the kind of robust cooperation with the Iraqis that we have with allies all over the world,” McDonough said.

President Obama convened a secure video conference this morning with Iraqi Prime Minister Nouri al-Maliki to talk with him about this news, a source said.

More than 1 million Americans have served in Iraq since the war began nine years ago. More than 4,000 troops have died, and over 32,000 injured during these years.

There are 39,000 U.S. troops in Iraq as of this week. From the beginning of operations through July 31, 2011, the Defense Department has obligated $704.6 billion for Operation Iraqi Freedom/Operation New Dawn (OND). The monthly cost of the war right now is about $3.8 billion.

Today’s announcement fulfills one of Obama’s central campaign promises. In 2002, Obama called the intervention a “dumb war” and as presidential candidate, vowed to bring troops home in his administration.

The Iraq war has become deeply unpopular among Americans. In a Gallup poll conducted in January, 66 percent of Americans opposed the war and a majority did not think it was worth fighting, given its costs versus the benefits.

ABC News’ Luis Martinez and Mary Bruce contributed to this report.