Obama and Cameron to present united front

David Cameron and Barack Obama in London in May last year (Getty Images)

Barack Obama and David Cameron today evoke the wartime partnership of Churchill and Roosevelt as they promise to stand shoulder-to-shoulder in tackling the turbulence in world trouble-spots and the global economic crisis.

Ahead of the Prime Minister's arrival in the United States for a three-day visit, they pay fulsome tribute to the links between the nations as "a partnership of the heart, bound by the history, traditions and values we share."

Mr Cameron, who will be welcomed to the US at a White House ceremony attended by 6,000 guests, will be honoured at a lavish state dinner.

He will also become the first foreign leader invited by Mr Obama to travel on the presidential jet, Air Force One, when the two men fly to watch a basketball game in Ohio.

Away from the pomp and the photo opportunities, the two leaders will hold talks on a daunting list of international problems. Afghanistan has leapt to the top of their agenda after an American soldier murdered 16 civilians during a night-time rampage, along with the repression of protesters by Bashar Hafez al-Assad in Syria and fears over Iran's growing nuclear capability.

The leaders will talk in detail about the departure of American and British forces from Afghanistan, starting with the handover of lead responsibility to Afghans in mid-2013. They will also discuss the struggle of Western nations to emerge from the economic downturn – the issue that has dominated both leaders' time in office.

In a joint article in the Washington Post today, Mr Obama and Mr Cameron insist they are proud of the progress against al-Qa'ida and the Taliban in Afghanistan, but acknowledge that recent events demonstrate it "remains a difficult mission ".

They pledge to "continue to tighten the noose around Assad and his cohorts," and insist they believe there is "time and space to pursue a diplomatic solution "over Iran" but warn that sanctions will be tightened unless Tehran meets its "international obligations".