The Afghan War was started in October of 2001. That means it will be 17 years old this coming October. That makes it the second longest war in United States history, if you count the Vietnam War as starting in the 1950's (when Eisenhower sent advisors there). It if count the Vietnam War as starting with the Gulf of Tonkin resolution (when the U.S. got serious about bombing and sending combat troops), then the Afghan War is already the longest war in our history. Why are we still there?
The original purpose of that war was to get Osama bin-Laden, who was responsible for the 2001 terrorist attack on New York City (and the Pentagon). That took longer than it should have, but it has been accomplished. Unfortunately, after invading Afghanistan, George W. Bush changed the mission. He wanted regime change -- i.e., forcing the Afghan people to accept an American-style government with our military power.
Sadly, Barack Obama and now Donald Trump have accepted that mission change and left troops in Afghanistan to continue the effort. Now it does not look like there will ever be an end to that war.
We have no business trying to tell the Afghan people what kind of government they should have. We would not allow a foreign power to dictate that to us, and shouldn't be trying to do that to them. Only the Afghan people have the right to determine how they will be ruled.
You might think that if we pull out the Taliban will take over. That may well be true. If the Afghan people want a Taliban government, that is their right. And if they don't, they will make the change themselves. Remember, far greater powers have been toppled by the will of the people (such as the Soviet Union, Poland, etc.).
The Russians tried to impose a soviet-style regime on Afghanistan -- and they came up against the same problem we now have (a continuing rebellion). They were smarter than us though, and after a decade they left. U.S. politicians have been too afraid to do that. They are afraid they will be blamed for "losing" that war. The truth is that it was never winnable. And it won't be winnable if we stay another 17 years.
We made a grievous mistake in trying to force a regime change on the Afghan people. It's time to admit that and bring our soldiers home. The pride of our idiot politicians is not worth the life of even one more American soldier.