Leaders of the United States and Britain have outlined plans to shift the NATO war effort in Afghanistan toward a back-seat advisory role while Afghan forces increasingly take the lead, but stressed that the two nations remain committed to the mission there.
President Barack Obama gave his fullest endorsement yet for the mission shift, but he said the overall plan to gradually withdraw forces and hand over security in Afghanistan will stand.
Obama said he anticipates no "sudden, immediate changes to the plan we already have," for bringing forces home.
The United States and Britain have the largest fighting forces in Afghanistan, where the combat is in its 11th year. The US, Britain and other NATO nations have already agreed to keep forces in the country through 2014, when Afghan President Hamid Karzai will leave office.
"At the upcoming NATO summit in my hometown of Chicago, we'll determine the next phase of transition," Obama said following a private meeting at the White House with visiting British Prime Minister David Cameron. "This includes shifting to a support role next year in 2013 in advance of Afghans taking full responsibility for security in 2014. We're going to complete this mission and we're going to do it responsibly."
Obama acknowledged the drop in public support at home for the war. "People get weary," after long wars, the president said, but he also said he thinks most people in both the US and Britain understand the reasons for continuing the fight.
Cameron, who joined Obama for a joint Rose Garden news conference, said security is better in Afghanistan and he praised the US strategy to add more than 30,000 forces in a "surge" against the Taliban-led militants in 2009.
"The situation is considerably improved," Cameron said, and the goal of keeping Afghanistan from again becoming a terrorist haven is achievable by the end of 2014.
Following the summer fighting season, Obama said NATO allies would look at how to continue drawing down forces at a gradual pace.
The Obama-Cameron meeting came in advance of May's NATO summit in Chicago, where a decision on the timetable for withdrawal from Afghanistan is expected to be confirmed.
The White House discussions follow the weekend killings of 16 Afghan civilians, allegedly by a lone US soldier, and the deaths of six British troops last week in a roadside bomb blast - the largest loss of life in a single incident for British forces in Afghanistan since 2006.
On Iran, Obama insisted there is still "time and space" for a diplomatic solution, in lieu of a military strike to set back Iran's progress toward a possible bomb, but said "the window for diplomacy is shrinking."
"We are determined to prevent Iran from acquiring a nuclear weapon," Obama said, adding that he had sent a message "personally" to the Iranian leadership that it should re-enter international arms talks in good faith.
"Tehran must understand that it cannot escape or evade the choice before it. Meet your international obligations or face the consequences."