So how should the US respond to Afghan election?

"The initial U.S. response should be more focused on maintaining calm than on assessing how free the elections were; it should leave space for Afghan reactions to dominate. All of the political steps that are bound to follow Saturday’s voting must be Afghan-driven, but this does not contradict the need for a strong U.S. diplomatic role in maintaining the peace. Afghan voters and leaders still care deeply about whether their political system appears democratic to outside observers, and they care about electing a leader the international community will do business with. Many will seek to know whom the United States “really supports”; while the Obama administration should remain neutral, we should not expect our show of neutrality to be believed. It would also have an effect if U.S. officials were to speak strongly against a candidate, as many Afghans would not vote for someone whose election would mean the end of U.S. or international aid. Washington would be wise to prepare for a role as a quiet referee and potential mediator in the negotiations over fraud that is likely to emerge. "