The United States has been engaged in combat in Afghanistan since 2001 and Iraq since 2003. I supported both of those missions and still believe they were the right thing to do. But here we are ten-plus years later. The Afghans remain in the stone age (we couldn't bomb them to that age, they were already there), Saddam and his regime are gone from Iraq, yet we still have troops in both places.
With the unrest in Syria and now Egypt, I suppose I can understand the reason for troops in Iraq. But to what end in Afghanistan? There is no clear national interest. The Taliban remain in-country, but are far weaker and will be unable to mount a wave of terror against the US.
I will not go for the emotionalism of the human cost - you can read about that in the sock-puppet media. It's an all-volunteer force.
There is no national interest in the Middle East any more. I believe we have a moral obligation to Israel, but that's just me. Otherwise, "declare victory an bring them home".