Vermont National Guard personnel have begun to deploy for their new mission to Afghanistan, and families have begun to shoulder the home front mission: carrying on despite the worry and loneliness that follow when a loved one is in a combat zone.

The worries connected with this mission may be magnified by the difficult task that the Guard has undertaken. Afghanistan is an alien place, and the foreign policy questions surrounding the U.S. mission are complex. The American public is cooling toward the war, and the Obama administration has been engaged for months in a serious re-evaluation of U.S. strategy. These are not the circumstances to put one's mind at ease.

The Vermont Guard will be part of a brigade whose principal job will be to train Afghan military, police and border patrol. It will be on-the-job training out in the field, not in a training camp or academy. It will be a crucial element of any future strategy, and it will have the risks that come with combat.

Policy decisions like those taking shape within the Obama administration do not occur in a vacuum. They must take into account everything that has happened before. Thus, the idea that we should not be engaged in Afghanistan is of limited usefulness. We can't pretend we are starting the policy from scratch and decide, out of the blue, that we no longer want to be there.

We are there, and we are there for reasons rooted in recent history. It was U.S. policy to arm Islamic insurgents in Afghanistan to help drive the Soviets out of the country. The Soviet exit created the chaos that led to the rise of the Taliban, a fundamentalist Islamic movement. The Taliban provided sanctuary and support for al-Qaida, which attacked the United States on Sept. 11, 2001. Driving out al-Qaida and the Taliban was a necessary response to those attacks.

The United States was not prepared to leave behind a power vacuum once again, and so the Western powers engineered the presidency of Hamid Karzai. His response to the power vacuum within his devastated nation was to ally himself with the regional warlords who held power in the provinces. Poor governance, corruption and big-time drug trafficking have created a new kind of vacuum — a vacuum of justice — that the Taliban have once more begun to fill.

It has been an article of faith that in order to counter the appeal of the Taliban the United States needed a strong partner in Kabul with effective security forces. That is where the Vermont Guard comes in. The difficulty is that Afghanistan is a devastated, primitive nation, with poor literacy, rugged geography, fractious ethnic divisions, and ungovernable tribal regions. Building an effective government and army is like persuading the 12th century to become the 21st.

And yet for the United States simply to vanish from the landscape would leave a region extending into Pakistan in chaos. It would be an unconscionable abdication of responsibility.

Republicans accuse President Obama of "dithering" as he considers these questions. Vermont's citizen-soldiers ought to be glad he is taking his time. There are regions of Afghanistan where it makes no sense for U.S. or even Afghan forces to try to extend their power. There are other regions that must be defended against the chaos that would be wrought by an expanded insurgency. Figuring out how to deploy U.S. and NATO forces in a land of 20,000-foot-high mountains and vast unpopulated deserts has required time.

The fiasco of the August election has revealed Karzai's weakness.

He won the election by default after his main challenger, Abdullah Abdullah, decided a runoff would be futile. Obama is now in the midst of determining what kind of partnership he will able to forge with Karzai and his troubled regime. The Vermont Guard will be there to do its job. It is an important one, and shrewd leadership at the White House could help make it a successful one.