Under intense security and the cover of night, President Barack Obama slipped into Afghanistan Tuesday to sign an agreement cementing a US commitment to the nation after the long and unpopular war comes to an end. Obama was to be on the ground for about seven hours in Afghanistan, where the United States has been engaged in war for more than a decade following the Sept. 11, 2001, attacks. The trip carries major symbolic significance for a president seeking a second term and allows him to showcase what the White House considers the fruit of Obama's refocused war effort: the killing a year ago of 9/11 mastermind Osama bin Laden. Air Force One touched down late at night local time at Bagram Air Field, the main US base here. Media traveling with Obama on the 13-hour flight had to agree to keep it secret until Obama had safely finished a helicopter flight to the nation's capital, Kabul, where Taliban insurgents still launch lethal attacks. Obama is joining Afghan President Hamid Karzai to sign the agreement that will broadly govern the US role in Afghanistan after the American combat mission stops at the end of 2014 — 13 years after it began. Obama will also give a speech designed to reach Americans in the US dinnertime hour of 7:30 p.m. EDT. It will be 4 a.m. here when Obama speaks. His war address will come exactly one year after special forces, on his order, began the raid that led to the killing of Bin Laden in Pakistan. Obama's overarching message will be that the war is ending on his watch but the US commitment to its ally is not. Politics, too, set the tone for what the White House hoped would be a positive message and image for Obama: the commander in chief setting a framework to end the war while reassuring Afghanistan, on its soil, it will not be abandoned. At home, Obama's Republican opponent, Mitt Romney, has retorted to the Obama campaign's suggestion that Romney might not have gone after bin Laden as Obama did.