President Obama made a surprise visit to Afghanistan on Tuesday to sign a strategic-partnership agreement with President Hamid Karzai. He arrived at Bagram Air Base before taking a helicopter to the presidential palace to sign the agreement. The pact pledges 10 years of U.S. aid after the withdrawal of troops in 2014. White House aides said that Obama traveled to the country to reassure Afghans that America will stand by them even after the troops have left. Obama also plans to address the American people from Afghanistan on the one-year anniversary of Osama bin Laden’s death.