He says we must be concerned about Pakistan because areas of the country already largely under the control of Al Qaeda were made even more unstable by recent disastrous flooding.
"We have a huge strategic interest in trying to see this through. This is Al Qaeda central and it's right next to Pakistan which is on the verge of being a failed state, and they have nuclear weapons and technology so this is something we really need to get right," said Marshall.
Marshall says the war in Afghanistan is a tough fight, but he says U.S. troops are making remarkable progress.
He says most Afghans want to be free of the Taliban but they have not had a reasonable security alternative.