U.S. troops are still in Afghanistan, nearly 11 years after they invaded. Why? The answer boils down to one word: al-Qaida. The goal is to damage the terrorist group enough to prevent a repeat of the 9/11 attacks.
Where they stand:
After nearly tripling the number of U.S. troops in Afghanistan in 2009-10, President Barack Obama is pulling them out, aiming to end all U.S. combat there by December 2014. He says Afghans are now "perfectly capable" of defending themselves, allowing U.S. troops to leave. Mitt Romney now endorses ending combat in 2014, saying flatly "we're going to be finished" then.
Why it matters:
Only small numbers of al-Qaida fighters are still in Afghanistan, and their iconic leader, Osama bin Laden, is long dead. But the threat they represent is still the main reason Americans are still fighting and dying there.
The logic goes like this: If U.S. and allied forces were to leave before the Afghans can defend themselves, the Taliban would regain power. And if they were in charge, then al-Qaida would not be far behind.
In that view of what's at stake, al-Qaida would once again have a launching pad for attacks on American soil.
What's harder to explain is why it has taken so long to train the Afghan forces. And what if it turns out that by 2014 they are losing ground against the Taliban? Would the U.S. send more forces back in to avoid a Taliban takeover? Asked that question directly in the final presidential debate, both Romney and Obama sidestepped, insisting that the U.S. combat mission will end on time.
From an American point of view, what is at stake in Afghanistan is avoiding a repeat of 9/11. But it is also true that the United States is war-weary and faces threats on other fronts. Some of those threats have arisen as a consequence of the U.S. invasion of Afghanistan in October 2001, just weeks after the traumatizing 9/11 attacks.
Al-Qaida has migrated to other countries such as Pakistan, Yemen, Somalia and various spots in North Africa.
Thus, al-Qaida remains a worry, but its presence in Afghanistan does not seem to trouble many Americans. Although 68,000 U.S. troops remain in Afghanistan and more than 2,000 have died there since 2001, the war is hardly an issue in the presidential campaign.
It's perhaps a measure of the public's inattention to Afghanistan that Defense Secretary Leon Panetta felt it necessary to say at a Pentagon news conference that it was important to "remind the American people that there is a war going on."
He added, with an allusion to the al-Qaida threat: "Young men and women are dying in order to try to protect this country."
The outcome in Afghanistan also is important because of the enormous investment in human lives over the past decade. To let it unravel and revert to a pre-9/11, Taliban rule would be seen by many as dishonoring those sacrifices.