The United States on Tuesday withheld $18 million in aid from Uzbekistan, a military ally in its war on terrorism, as a punishment for what it has called unacceptable human rights violations. The move followed human rights groups\' calls for the United States to block the funds, in a case that highlighted Washington\'s dilemma in working with authoritarian governments to hunt militants. The United States said it intends to continue military cooperation with Uzbekistan. The Central Asian nation allows Washington to use an air base for operations in neighboring Afghanistan. \"Uzbekistan is an important partner of the United States in the war on terror and we have many shared strategic goals. This decision does not mean that either our interests in the region or our desire for continued cooperation with Uzbekistan has changed,\" the State Department said. Congress required the Bush administration, which has been criticized for sacrificing human rights in pursuit of security, to certify that Uzbekistan had made substantial progress on human rights and democracy in order to disburse the aid. Human Rights Watch said the decision to withhold the aid showed the United States was serious about pressing for improvements in Uzbekistan. The aid was intended to pay for programs ranging from law enforcement to improving the accounting standards of Uzbekistan\'s central bank. \"There is still a carrot out there for Uzbekistan. The carrot is recertification and gaining stature on the international stage for coming through and making improvements,\" said Rachel Denber of the New York-based Human Rights Watch. Thousands of political and religious prisoners, mainly Muslim dissidents, are incarcerated on flimsy pretexts in Uzbekistan, according to human rights groups, who accuse the government of torture. Uzbek officials have said torture is no longer systematic in the jails of the former Soviet state. But the United States has complained it is \"unacceptable\" that deaths in detention have gone unpunished. (Reuters)