Afghanistan holds little strategic value for us - Saudi Arabia, Egypt, Israel, Kuwait, the UAE, Turkey, Oman, and Iraq, on the other hand, do.
We retain sizeable forces in Germany, Japan, and the ROK over a half-Century after the initial reasons for our deploying there because it remains of mutual strategic importance for us and our allies to do so.
If it is truly of strategic importance to us, we will seek to retain a viable presence in Iraq for as long as necessary, too.
Richard's $.02