The Afghanistan war was forgotten during the 2016 presidential campaign although the war is the longest American war in US history. After 16 years including NATO participation, the war is inconclusive - there is no peace and seemingly no end. The war has been between U.S./NATO and the Taliban. Originally the Taliban conquered many towns and provinces without fighting as the townsmen welcomed them because they were disappointed with the mujahidin internal intrigue just the same as the American public who were disappointed with the established political order in Washington during 2016 election that led to the victory of President-Elect Donald Trump.
The Taliban had control of Afghanistan when the tragedy of Bin Laden's 9/11 took place and caused a regime change in Afghanistan on October 7, 2001. The subsequent U.S. appointed regimes failed to make peace with the Taliban and bring into the fold the 30 million Afghan citizens.
Needless to say, the American war must end by President Trump as it has no purpose to continue. The engagement of NATO members in Afghanistan was arguably unlawful. The North Atlantic Treaty initially included 12 memberships in 1949. Its mission was a collective defense pact against the threat of the Soviet Union to protect Europe. The membership has been expanded to currently 28 countries. Under article 5 of the treaty an attack on any member is considered an attack on all members. However, the Soviet Union never attacked a member of NATO and therefore its provision was never put to use until the US-led invasion of Afghanistan.
The United States pressured NATO members to participate in the invasion of Afghanistan plus several additional non-NATO members such as Korea. NATO participation in Afghanistan has been a tragic failure, as evidenced in the British contingent in Helmand and the French contingent in the southern provinces of Afghanistan. Moreover citizens of France and England demonstrated against the war in Afghanistan and pressured their governments to withdraw their troops which they did prematurely. Besides the engagement of NATO in Afghanistan was arguably illegal as Afghanistan had not invaded any of the NATO member countries and therefore NATO's article 5 provisions did not apply in the particular case of Afghanistan. Historically, Afghanistan has had good relations with European countries.
During the U.S. presidential campaign candidate Trump opted to modify or withdraw from subsidizing NATO. President Trump should use this lever to redefine US Afghanistan policy.
Currently the Taliban appears to be prepared to make peace, negotiate with the U.S. government, and offer many advantages including eliminating the presence of ISIS and other Arab insurgents groups from Afghanistan soil and end Pakistan's long-term duplicity vis-i-vis U.S. interest. President Trump should not miss this opportunity to finally end the war.