Afghanistan top of the agenda for Cameron's trip to Washington

US visit set to start with agreement to end lead role in conflict – but more divisive issues lie ahead

British and American troops would be pulled back from frontline combat roles in Afghanistan by the middle of next year under moves to be discussed by David Cameron and Barack Obama tomorrow. Greater detail of the proposed withdrawal of US and UK forces emerged as the Prime Minister prepares to fly to the United States today for a three-day state visit expected to be dominated by Afghanistan.

The issue has been forced to the top of the leaders' agenda after an American soldier massacred 16 Afghans, including nine children, during a night-time rampage. Mr Cameron believes responsibility for frontline duties can be passed to Afghan forces by mid-2013, with American and British troops withdrawing in full by the end of 2014.

Both leaders said yesterday that, despite the carnage at the weekend, there should be no loss of nerve in sticking to the timetable.

Ahead of a summit that will also ripple with hidden tensions on defence spending, Europe and the Falkland Islands, the two men attempted yesterday to evoke the wartime partnership of Churchill and Roosevelt pledging to stand shoulder-to-shoulder on the world stage.

The preferred public mood music of the visit starting tonight is struck up in a joint opinion article by the two leaders in today's The Washington Post that portentously trumpets the links between the nations as "a partnership of the heart, bound by the history, traditions and values we share".

Mr Cameron will be welcomed to the US at a White House ceremony attended by 6,000 guests, feted at a state dinner tomorrow and 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.

The reality, however, is of a relationship hurt by inattention, notably from the US side. Washington supports Argentina's call for UN talks on the Falklands and has shown a keen interest in a more federal European Union. The old bonds of defence policy have also been worn thin by budget cuts on both sides.

Mr Obama and Mr Cameron must tackle the repression of protesters by Bashar al-Assad in Syria and the nuclear stand-off with Iran.

"The least desirable outcome of the summit would be for Britain and the US to paper over these important issues and declare that the summit is a success by focusing on visuals and the drafting of an agreed communiqué. Regrettably, this is also the most probable outcome," said Ted Bromund, a senior research fellow at The Margaret Thatcher Centre for Freedom at the Heritage Foundation in Washington. In a joint article today, Mr Obama and Mr Cameron write: "Seven decades ago, as our forces began to turn the tide of World War II, Prime Minister Churchill travelled to Washington to co-ordinate our joint efforts." They quote Churchill's observation that battlefield victories proved "what can be achieved by British and Americans working together heart and hand" and his hope that "if they could keep it up, there is hardly anything they could not do, either in the field of war or in the not-less-tangled problems of peace".

The leaders 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.

The itinerary

Today Arrive in Washington. Obama and Cameron fly to basketball match in Ohio.

Tomorrow Welcome ceremony at White House. Talks in Oval Office, followed by official luncheon. l State Dinner Guests include old Etonian actor Damian Lewis and golfer Rory McIlroy.

Thursday Meetings in New Jersey and New York.

Still special - relations through the years

Winston Churchill (1940-45) and Franklin D Roosevelt (1933-45)

When Churchill delivered his "Iron Curtain" speech in 1946, he also coined a term – "special relationship" – which has haunted every US president and British prime minister since. However, Roosevelt is believed to have seen their "friendship" as a matter of wartime convenience. Harold Macmillan (1957-63) and John F Kennedy (1961-63)

Both leaders said they had enjoyed mutual trust until Kennedy cancelled the joint Skybolt missile programme in 1962 without consulting Macmillan. But the Nassau agreement, which confirmed that the US would sell Polaris missiles to the UK instead, soon healed the wound.

Harold Wilson (1964-70) and Lyndon B Johnson (1963-69)

The Vietnam War was the bone of contention between these two. Wilson's Labour government refused to support the war, and rejected numerous requests by the Johnson administration for combat troops.

Margaret Thatcher (1979-1990) and Ronald Reagan (1981-1989)

Although they agreed on most policy matters, the two enjoyed sparring with each other. On one occasion, when Thatcher was complaining loudly at him down the phone line, Reagan reportedly held the phone up so his colleagues in the room could hear her and exclaimed: "Isn't she marvellous!"

Tony Blair (1997-2007) and George W Bush (2001-09)

Blair and Bill Clinton were said to have been political "kindred spirits". But Blair's partnership with Bush in the aftermath of 9/11 took the alliance to a new level.