“I would guess the U.S. has to plan on being inside Afghanistan for a decade or more in order for there to be any type of resolution,” said Bill Roggio, editor of Long War Journal. “It’s definitely past his first term in office, no two ways about it.”

The Green Zone expansion is aimed at making it possible for America and its NATO allies to remain in the capital without facing the risks that have in the past year made Kabul the most dangerous place in Afghanistan, with more people killed there than anywhere else in the country — mostly from suicide bombers.

Kabul’s security area had long been a Green Zone-lite compared with its fortresslike predecessor in Baghdad, where there are massive blast walls and a total separation from the general population, enforced by biometric entry passes.

In Kabul, thousands of Afghans still commute to jobs and even schools inside the zone, with only light searches for most of them, mindful of the resentment stirred by the Soviets’ heavily militarized central zone during their Afghan occupation. And the Green Zone in Baghdad has, its critics maintain, created an out-of-touch ruling class and Western community, and provided a magnet for protests while just moving enormous bombings elsewhere, further stoking popular discontent with leaders and foreigners.

The Kabul Green Zone expansion, which will significantly restrict access, was prompted, according to both Afghan and American military officials, by a huge suicide bomb planted in a sewage truck that exploded at a gate of the current Green Zone on May 31, destroying most of the German Embassy and killing more than 150 people. The loss of life could have been far worse, but Germany had evacuated its embassy a week before the bombing, apparently tipped off by intelligence sources.

The military recently appointed an American brigadier general to take charge of greatly expanding and fortifying the Green Zone. In the first stage of the project, expected to take from six months to a year, an expanded Green Zone will be created — covering about 1.86 square miles, up from 0.71 square miles — closing off streets within it to all but official traffic.