Austin , Texas ( CNN ) -- The past month has been the worst for the United States in Afghanistan since the war began after the attacks of September 11 , 2001 . There have been more difficult periods of combat against the Taliban , al Qaeda and other insurgents . There have been more fragmented and confused moments in allied strategy . There has , however , never been a time when American soldiers acted with such obvious and offensive disrespect for Afghan citizens . The past month has witnessed a string of incidents , including the alleged killing of 16 civilians by a U.S. soldier and the burning of Qurans , the holiest touchstone of the Islamic faith , at a NATO air base . The United States has crossed a self-defeating threshold in Afghanistan where our soldiers are seen as attacking the very people and culture they are deployed to protect . We are destroying villages in order to save them . We have witnessed this dynamic before . In early 1968 , it became apparent that American soldiers in South Vietnam were fighting a stubborn communist enemy without the support they expected from South Vietnamese citizens . To the contrary , residents of South Vietnam frequently gave assistance to the insurgents killing Americans . Frustrated and desperate , particularly after the Tet Offensive in January 1968 , American soldiers took the war to the population with devastating consequences . Counterinsurgency warfare meant burning rural villages , bombing crowded areas and killing innocent civilians . The My Lai massacre of March 16 , 1968 , was the most notorious example , but it was not unique . After failing to catch insurgents who fled the village , angry American soldiers killed more than 300 women , children and elderly residents in cold blood . The United States was massacring the same South Vietnamese it was fighting to save . We do not know what motivated the American soldier who is accused of going house-to-house , murdering Afghan families , on Sunday . Based on the patterns of the past month , the question arises : Was he acting in ways that echo My Lai ? The U.S. military might be the strongest fighting force in the world , but it is still a collection of emotional and fragile human beings who react to the circumstances , pressures and incentives around them . As in Southeast Asia more than 40 years ago , the American soldiers in Afghanistan are fighting a war against an elusive enemy amidst a population that is increasingly resistant to American demands for assistance . Afghan citizens know that the United States is planning to leave soon , and they sense that the Americans they meet care more about an `` exit strategy '' than the welfare of their society . Afghan intransigence furthers the frustration and resentment among American soldiers , fueling violent behavior directed at innocent civilians . This self-defeating cycle reflects specific policies . President Barack Obama has acknowledged the corrupt Afghan leadership of Hamid Karzai , but he is doing nothing serious about it . The U.S. government has told its more than 80,000 troops in Afghanistan that they must help create a stable and secure Afghan nation , despite rampant corruption , in less than a year . Young American soldiers are under enormous pressure , in hostile circumstances , and they are increasingly isolated from support networks within the United States . For all the talk of `` supporting the troops , '' the Afghanistan war receives little serious attention in American public debate . Obama rarely mentions the war , and his Republican challengers say little about it either . The American soldiers in Afghanistan are under orders to do the impossible at light speed , and they are ignored by their fellow citizens . We have re-created the conditions of extreme stress , isolation and victimization that were evident in Vietnam . We have turned a frustrating war into a breeding ground for American atrocities . This is what happens when our national leaders try to fight a war and exit a war at the same time . We can not do both . Our soldiers can not build a functioning nation when they are told that we are not doing nation-building . They can not defeat an enemy when we refuse to engage fully . They can not work peacefully with local citizens when they are told that local citizens are the problem . The choice is not to use more firepower or withdraw . The real choice is whether the United States is committed sufficiently to Afghanistan and willing to invest in supporting long-term efforts that will give our soldiers and local citizens a reason to believe that things will get better . If the United States is unwilling to make these commitments , then it should admit it and reduce the demands on its soldiers . Either way , Americans must create a realistic basis for their activities in Afghanistan and end the fiction of a smooth transfer of authority from our overburdened soldiers to Karzai 's corrupt administrators . Realism will not please many Americans , but it will at least help to reduce the cycle of atrocities in Afghanistan . The time has come to escape the worst dynamics of Vietnam and re-learn the limits of American power . The opinions expressed in this commentary are solely those of Jeremi Suri .
A killing spree in Afghanistan follows Quran-burning incident . Jeremi Suri says the U.S. has had its worst month in the long Afghan war . He says it 's reminiscent of Vietnam War , when soldiers turned against population . Suri : U.S. leaders are failing to set and pursue achievable objectives .