Obama hails UK alliance as 'indispensable'

Obama went out of his way to offer Cameron lessons to learn the rules of cricket, gifting his guest a top of the range American grill, and laying on a sumptuous state dinner.

But both men were forced to dwell on the costs of war, with sharp questions looming about the justification for more combat in Afghanistan and the possibility of new Middle East combat over Iran's nuclear program.

Obama and Cameron conspicuously used a joint press conference to try and convince weary American and British voters that recent sacrifices in Afghanistan had wrought "real progress" towards a future secure state.

The US leader went on the record for the first time to back NATO's planned transfer to a support role in 2013 before a full withdrawal the next year, though said there would be no sudden unscheduled draw-downs in coming months.

The Obama's hosted a sumptuous state dinner for the Cameron's  Cameron with seats at the tables for more than 350 celebrities, billionaires and politicians.

Held in a marquee on the White House's south lawn, Obama paid tribute to Cameron saying: "I've seen his character, I've seen his commitment to human dignity in Libya. I've seen his resolve, his determination to get the job done."

And in an apparent reference to the couple's care for their disabled son Ivan, who died in 2009 aged six, the president said: "I will say something else, David: all of us have seen how you as a parent along with Samantha have shown a measure of strength that few of us will ever know.

"Tonight I thank you for bringing that same strength and solidarity to our partnership."

Cameron responded by saying he felt the special relationship "in his bones".

He praised President Obama's "strength, moral authority and wisdom", citing his decision to order the mission which led to the death of Osama bin Laden.

"Let us all agree, the world is better off without bin Laden but the world is better off without Gaddafi too," Cameron said.