Published on Oct 7, 2018 After 17 years long, the war in Afghanistan is now considered the longest-running war in U.S. history. But why did the United States invade Afghanistan in the first place, and is anyone winning this war? The war in Afghanistan is now 17 years old - making the Afghanistan war the longest-running war in United States history. To put that number into perspective, young Americans can now enlist to fight in a war that began before they were even born. The war in Afghanistan that was started under President Bush and continued under President Obama, is now in the hands of President Trump -- who's taken a drastically different approach to the Afghanistan war than his predecessor. And making sense of Trump's Afghanistan war strategy and the us forces in Afghanistan has been on the minds of many.