Why Afghanistan is important for USA?

Primarily, USA started its venture of  Afghanistan as an effort to uproot the Al-Qaida which was at that time having its operational bases under the Taliban Regime. So the Afghanistan was the destination of war against terror. At that time it was first attempted to get all  wanted person through negotiations but Taliban rejected all these offers. Afghanistan was over run by the USA and other allied forces but what came next was more important for USA and the rest of world.

Taliban although defeated at the hands of USA were making strong inroads. Moreover, there was a perception that USA has exploited the Afghan people back in 1979 against the Russian. So this time USA was going to built its credibility in the region. 

Maintaining this status USA started its initiative to built the society and infrastructure in Afghanistan. But there was a more confusing situation with USA stay in Afghanistan. As Taliban were emerging time and again in Afghanistan. They were making their summer attacks so it gave a reason to USA to prolong its stay in Afghanistan. But generally USA and the world proposed an exit of USA from Afghanistan as and ultimate way to settle Afghanistan issue.

There were multiple options to keep the quagmire of Taliban in limit. First of all it was proposed that Taliban should be included in political process of  Afghanistan but Taliban always remained averse to it. So the this challenge was the main factor to prolong the stay of USA in Afghanistan. This was the main objection against USA as well.

But for USA it is more important to built a prosper Afghanistan as a strong and growing Afghanistan is  necessary for USA. Because if USA leaves Afghanistan in such a situation, it is going to created  mess not only for USA but also for Afghanistan.

So  all these factors contribute to add Afghanistan in  interests of USA. But indeed prosper and strong Afghanistan is important for world.