Is it any wonder that Islamists are vastly more popular than we are in Afghanistan? That is not going to change — which is why the Afghan army’s 9:1 numerical advantage over Taliban forces, even compounded by 130,000 coalition troops and another 130,000 Afghan national police, is unable to win the day, despite the prohibitively costly decade our troops have spent struggling to train them.

Before or after American forces leave, the Taliban — whether by negotiated settlement or brute force — may take over the country. Or, more likely, the Afghan civil war, which neither we nor the Taliban started, will simply continue. The Taliban and Haqqani will go on vying with Karzai’s regime, Hekmatyar’s Hizb-e-Islami, and the rest of Afghanistan’s motley assortment of warlords and tribal rivals.

We do not need the Taliban to lose. We need those factions that capture territory to be deeply discouraged from inviting al-Qaeda to return, set up shop, and launch attacks against the United States. The senators are wrong to insist that this requires a continuing, weighty presence of American forces in a hostile place. We currently face this same challenge in several Islamic countries absent occupation by thousands of ground troops.