In our letter to the president, my Senate colleagues and I urged him “to follow through on the pledge he made to the American people to begin redeployment of U.S. forces from Afghanistan this summer, and to do so in a manner that is sizable and sustained, and includes combat troops as well as logistical and support forces.”

In 2001 the United States rightfully -and successfully- intervened in Afghanistan to destroy al-Qaida's safe haven and pursue those who planned the September 11 attacks on our nation. CIA Director Leon Panetta believes we have accomplished our goal when he recently said: “I think at most, we're looking at maybe 50 to 100, maybe less” al-Qaida members remaining in Afghanistan.

Our Afghan policy has succeeded. Over the past few years, U.S. forces have killed or captured dozens of al-Qaida leaders. On May 1, American Special Forces killed Osama bin Laden, a major blow that further weakens the terrorist organization.

Given our successes, this is the right time to initiate a sizable and sustained reduction in forces, with the goal of steadily redeploying all regular combat troops.

Some have argued that rather than reduce our forces, we should maintain a significant number of troops to support a lengthy counter-insurgency and nation building effort. I do not agree. We will never be able to secure and police every town and village in Afghanistan. Nor will we be able to build Afghanistan from the ground up into a Western-style democracy.

In fact, endemic corruption in Afghanistan has diverted resources intended to build roads, schools and clinics, and some of these funds have ended up in the hands of the insurgents. While it may be laudable to attempt to build new civic institutions in Afghanistan, it does not justify the loss of American lives or the investment of hundreds of billions of taxpayer dollars.

With our overall objectives met, now is the time to accelerate the transfer of responsibility for Afghanistan's development to the Afghan people and their government. We should maintain our capacity to eliminate any new terrorist threats, continue to train the Afghan National Security Forces, and maintain our diplomatic and humanitarian efforts, but these objectives do not require the presence of more than 100,000 American troops.

Sen. Cardin is a member of the Foreign Relations Committee and co-chairman of the U.S. Helsinki Commission.