WASHINGTON - President Barack Obama, attending his first Army-Navy football game as commander in chief at the weekend, praised the dedication of the country's armed forces ahead of a week in which he will focus heavily on the end of America's war in Iraq.

"As much fun as these things are, part of what we celebrate is the dedication and the sacrifice all these young men and young women who are in the stands are going to be making for our country," Obama told the game's commentators during the first half of the contest between the US Army and Navy academies.

All US forces are expected to get out of Iraq by December 31, fulfilling an Obama pledge to Americans tired of the nearly nine-year-old war as the president accelerates his campaign for re-election next year .

High unemployment and the fragile economy will weigh more with voters than costly foreign wars. But Obama will try to keep the spotlight next week on what he sees as a key national security accomplishment, alongside the killing of al Qaeda leader Osama bin Laden by US forces in May.

Iraqi Prime Minister Nouri al-Maliki visits the White House today and will travel with Obama to Fort Bragg, North Carolina, on Wednesday where the president and first lady Michelle Obama will thank soldiers returning home from Iraq.

Almost 4500 US troops have died in Iraq since President George W Bush ordered the invasion more than eight years ago, based on allegations of weapons of mass destruction that turned out not to exist.

Greeted loudly by the crowd of 80000 that filled Fedex Field outside Washington for the 112th annual competition between two of the oldest rivals in American college football, Obama tossed the coin at the start of the game.

Under bright blue skies, and following a flyover by F-18 fighter jets and Apache helicopters, the president spent the first half of the game with Navy, chatting with midshipmen and Defence Secretary Leon Panetta, who also attended the game, as well as Vice President Joe Biden.

At half-time, he crossed the field from the Navy side to the Army side of the stadium, striding between a file of Army cadets in grey and Naval midshipmen in blue.

During half-time, Obama and Biden visited about 70 wounded service men and women, the White House said.

Donning a headset, Obama told the game's commentators that he had enjoyed playing high school football - until his classmates started getting bigger than him.

"I played football in ninth grade and then I realised I was built more for basketball," Obama said.

"I was a big kid in eighth grade and then in ninth grade suddenly everybody else started getting a little heavier than me."

The Navy beat the Army 27-21 for its 10th victory in a row.