The United States\' presence in Afghanistan is suffering illegitimacy and Americans should accept that they are at end of the road in this country, a former Afghan envoy said on Tuesday.\"Americans should accept that they have reached a dead-end in Afghanistan, and that resolving this problem by means of hardware methods is impossible,\" Afghanistan\'s former Ambassador to Kazakhstan Aziz Aryanfar told FNA on Tuesday. He further reiterated Iran\'s key role in resolving regional issues, and said Washington cannot solve the Afghan problem without Iran\'s contribution. \"Without an understanding with Iran and Russia which are two great countries of the region, The United States cannot resolve Afghanistan\'s problem either in the political or in the security spheres,\" the former envoy stated. His words came as the US officials are trying to convince Afghanistan to consent to the establishment of permanent US military bases in the war-torn Muslim state. Afghan President Hamid Karzai has tried to calm the concerns of his neighbors by saying any agreement signed with the US will be in \"the political, economic and military interest of Afghanistan\" and the precondition of any agreement would be \"the establishment of peace and the provision of stability in Afghanistan.\" But the regional countries, including Iran, have voiced strong opposition to the plan and called for the rapid withdrawal of the US forces from Afghanistan. Iran has repeatedly warned against possible plans for the establishment of permanent US military bases in Afghanistan, stressing that the bases would be a source of permanent insecurity from Iran\'s neighbor.