kabul international military mission afghanistan fail troop level reduce potentially dangerous repercussions rest world delegation u.s. lawmakers warn visit kabul monday fifteen years american-led operation topple taliban response september 11 2001 terrorist attack president barack obama consider whether maintain current level 9,800 u.s. troop reduce 5,500 end year current plan call guarantee success keep 9,800 ensure failure go 5,500 republican senator lindsey graham tell reporters kabul hard time support continue presence fair leave behind ... job go 5,500 place fall apart quickly graham join u.s. senators john mccain benjamin sasse joe donnelly visit time bipartisan delegation could visit troop independence day holiday obama administration decide troop level sooner rather late mccain say argue reduce number troop could lead repeat disaster iraq islamic state militants seize major cities wide swathe territory mccain republican chairman senate arm service committee sharply criticize white house decision last year restrict u.s. force target taliban fighters except self-defense limit circumstances rule recently relax recommendation american commanders kabul mccain say almost criminal restrictions place year rule engagement restrictive give advantage taliban terrorist group senator say lawmakers highlight afghanistan history one original havens al qaeda terrorists plead patience ultimately go win fight go take decades sasse say american people well understand stay partner good ally like afghan government best way deny future safe havens would plot jihadi attack across globe u.s. senators warn troop cut afghanistan