In the end, President Obama was forced to listen to his generals — not his political instincts — on Afghanistan troop levels, and he decided to split the difference. Mr. Obama is keeping 5,500 troops in Afghanistan beyond his presidency, about half the strength recommended by his top general in-country. It marks the sixth time he has rejected the advice of a ground commander on the force size in the long Iraq and Afghanistan wars. Military experts call that streak unprecedented for a commander in chief.

Like the current 9,800 U.S. troops there, the drawdown force of 5,500 will maintain a noncombat stance in training Afghan forces and hunting al Qaeda terrorists, Mr. Obama said Thursday. Administration officials said the U.S. will spend about $14.6 billion a year to house the troops at a total of four bases in Kabul, Kandahar, Jalalabad and Bagram — an increase over the estimated $10 billion annual cost of keeping a force at the U.S. Embassy in the Afghan capital.The president had wanted to deliver a speech saying that all American troops were out of Afghanistan at the end of next year, as he did in 2011 for the U.S. withdrawal from Iraq. But he was swayed by the dark picture of the Afghan conflict that the top brass has been drawing for him, and now Mr. Obama will pass the war onto the next president in 2017. MORE