By Alex Stevenson Follow @alex__stevenson
Britain and the United States' alliance is a "partnership of the heart", David Cameron and Barack Obama have declared.
The pair underlined the enduring nature of the much-cited 'special relationship' between Britain and the US in a joint article for the Washington Post newspaper.
They insisted there is "hardly anything we cannot do", echoing the words of Second World War PM Winston Churchill, after addressing some of the biggest problems faced in the world today.
"The alliance between the United States and Great Britain is a partnership of the heart, bound by the history, traditions and values we share," they wrote.
"But what makes our relationship special — a unique and essential asset — is that we join hands across so many endeavours. Put simply, we count on each other and the world counts on our alliance."
Mr Cameron and Mr Obama said there remained "time and space to pursue a diplomatic solution" against Iran's nuclear agenda, but their private talks on the three-day visit are expected to address growing calls for military action.
"As the United States imposes its strongest sanctions to date and the European Union prepares to impose an embargo on Iranian oil, the choice for Tehran will be sharpened — meet your international obligations or face the consequences," they added.
The Middle East remains a challenging area for Britain and the US. They reaffirmed their commitment to the "brave citizens" calling for more democracy across the region and pledged to "continue to tighten the noose" against Bashar al-Assad's regime.
Both countries are reeling from the news of a rogue US marine's rampage in Afghanistan, setting the bid to stabilise the country back significantly.
Mr Cameron and Mr Obama are preparing for an upcoming Nato summit in Chicago in which they will seek to end their troops' combat role in Afghanistan by the start of 2014.
They both underlined the steps they were taking to "care" for their troops when they return home in an attempt to recognise "our obligations to troops and veterans endure long after today's battles end".
Mr Cameron will be the first foreign leader to travel on Air Force One as he journeys to Ohio to watch a baseball game.
"Our troops and citizens have long shown what can be achieved when British and Americans work together, heart and hand, and why this remains an essential relationship — to our nations and the world," the pair concluded.
"So like generations before us, we’re going to keep it up. Because with confidence in our cause and faith in each other, we still believe that there is hardly anything we cannot do."