Two Army Black Hawk helicopters fly over Logar province in Afghanistan earlier this month

Two Army Black Hawk helicopters fly over Logar province in Afghanistan earlier this month U.S. Army by Capt. Peter Smedberg

Just the Beginning: Afghanistan Troop Deal Prelude to Another Half Decade of War

This is not the end. After the security agreement, U.S. involvement in Afghanistan’s conflict is far from over. By Anthony H. Cordesman

The current debate over a bilateral security agreement with Afghanistan disguises far more serious challenges in the years to come. The BSA is a necessary first step in creating the conditions for United States troops to stay in Afghanistan and function there. But even if Afghan President Hamid Karzai can be persuaded to stop manipulating the issue in an effort to gain domestic political support, it is only a prelude to the real challenges the U.S. faces in staying in Afghanistan.

First, the United States must make hard choices as to how many U.S. troops it will keep in country, their role as advisors and enablers to the Afghan forces and how much money it is willing to pay to keep the Afghan forces combat capable. Senior U.S. officers have said it will take some 11,000 to 13,600 U.S. and allied troops to support Afghan military and police forces through at least 2016, and these estimates seem all too accurate given the problems in Afghan forces -- particularly the police elements. It will also take some $3 billion to $5 billion in aid, although all of this aid does not have to come from the U.S.

The U.S. will also be advising forces that cannot now defeat the Taliban, Haqqani Network and other insurgents. They can only create a layered defense that may be able to secure most population centers and key lines of communication. U.S. combat forces will leave a nation very much at war, and the U.S. cannot predict how much aid and assistance Afghanistan will need.

Second, the U.S. must work with its allies to provide economic aid indefinitely into the future at a time when most aid workers will have left the field, aid has made remarkably little progress to date in creating real development and Afghan corruption has wasted much of the funding the country has received. The U.S. also faces the risk that the sudden cuts in military and civil aid and spending will trigger a serious recession in the market-driven aspects of the Afghan economy.

This means billions more in aid will be needed through at least 2018. Yet, no one can seriously calculate how much, at present, and how much the U.S. will need to contribute. Furthermore, it is far from clear that Afghanistan will come close to meeting the pledges it made at the Tokyo conference in 2012 to provide for economic reform and fight corruption, and no one knows what will replace the failed UN effort to try to plan and manage a meaningful aid and development effort. Without decisive actions in these areas, aid dollars will often do little more than enrich power brokers and disappear into foreign accounts.

(Read more: Will Corruption Force U.S. Troops to Abandon Afghanistan?)

Third, these uncertainties are compounded by the gross corruption and incompetence of an Afghan government that faces a presidential election in the spring of 2014. This election could bring a weak or corrupt and factional leader to power, take four to six months of a critical transition year to create a new, functioning government, and reopen all of the issues raised by the BSA even if Karzai signs it before the election. The failed constitution that gives so much power to the president makes the election critical, but no one knows who will win, whether the Afghan people will accept the result or what will happen to Afghan governance and political unity.

Fourth, the withdrawal of almost all U.S. and allied forces means that Pakistan and Iran will come to play a far more influential role in Afghan affairs, particularly since the Taliban and insurgent sanctuaries in Pakistan will be a strong as ever. Pakistani pressure, and Afghan politics, may well mean that the United States will be caught in the middle, and see one barrier after another raised to any use of U.S. forces to fight the threat of terrorism. The end result could be to leave the U.S. committed to aiding an Afghanistan that plays no meaningful role in the war on terrorism.

Fifth, desirable as a peace settlement might be in theory, such a peace could suddenly impose a whole new set of constraints on the U.S. -- if not require the withdrawal of all U.S. forces. The Taliban senior leadership has made it clear that it sees “peace” as an extension of war by other means, while the new Northern Alliance has made it clear it could reject any such peace and divide the country.

This is a long list of risks to deal with. It does not mean the U.S. cannot deal with them, or that the war in Afghanistan cannot be won over time. It does mean, that the debate over the BSA is at most step one in a complex series of more serious challenges, the U.S. will have to adapt to conditions it cannot now predict and any U.S. involvement with a change of success does require men, money and at least a half decade of further effort. The Afghan conflict is already the longest war in U.S. history, but if a workable BSA is agreed upon, it is anything but over.

Anthony H. Cordesman is the Arleigh A. Burke Chair in Strategy at the Center for Strategic and International Studies.