Click above for full-scale map

Human rights groups are lining up to pressure Congress not to authorize the provision of U.S. military aid to the Central Asian country of Uzbekistan, even though such assistance could prove crucial to getting supplies into and out of Afghanistan.

With the Obama administration weighing whether to request a waiver that would allow military aid to Uzbekistan for the first time since 2005, the groups recently sent a letter to members of the Senate pleading with them to oppose any such move, saying, “Uzbekistan’s status as a strategic partner to the United States should not be allowed to eclipse concerns about its appalling human rights record.”

The issue of military aid to Uzbekistan is a complicated one, but goes to the heart of the U.S.-led military campaign in Afghanistan. Uzbekistan has been prohibited from receiving military aid since government security forces there massacred demonstrators six years ago, and the authoritarian state has carried out a host of human rights abuses since that time.

For Washington, however, the government of Islam Karimov matters more now than perhaps at any other time in the history of their relationship.

U.S. military officials remain leery that Pakistan, a sometimes fickle ally, could cut off its supply routes to American troops in Afghanistan — as it has done for limited stretches in the past. And if that happens, Uzbekistan becomes the best transhipment point into the war zone.

The country already serves as a vital route for supplies into Afghanistan, but the Pentagon wants to expand its agreement to allow for additional equipment to get in. As the U.S. military prepares to pull out one-third of its forces by September 2012, it also wants permission to withdraw vehicles and other materiel from Afghanistan through Uzbekistan.

But in exchange for the expanded agreement, Uzbekistan is calling for support for its security forces — a prospect that rights groups find abhorrent because it could bestow legitimacy on a government that even the U.S. State Department has said forbids free elections, arbitrarily arrests members of the opposition and restricts freedom of speech.

“The U.S. government should make clear to the Uzbek government that direct assistance to its armed forces and security services will not be made available absent meaningful human rights improvements, including the release of imprisoned pro-democracy activists, an end to harassment of civil society groups, and effective steps to end torture,” the rights groups, including Human Rights Watch and Amnesty International, wrote in their letter to senators.

Freedom House, a Washington-based advocacy group that is among the other signatories, has previously ranked Uzbekistan as one of the nine worst countries in the world for civil liberties and political rights.

Still, there’s little doubt that improved relations with Uzbekistan could assist in the war effort. There’s a vast distribution network to get supplies to troops in Afghanistan, but Uzbekistan just happens to be in the strategically perfect place.

“In reality, Uzbekistan is really at the center of all these routes,” Alexander Cooley, a Barnard College professor and an expert on U.S. military relations in Central Asia, told The Post earlier this summer. “They’re certainly in the catbird seat. And they know it.”

None of which seems to override the concerns of the rights groups, which are making their case in part by pointing to the house of cards that has become of authoritarian governments in the Middle East, where societies “held together by fear and repression ... will eventually tear asunder,” as President Obama put it in May in his remarks on the Arab Spring.

The United States, the rights groups wrote, “need not — and should not — provide more concessions and rewards until the Uzbek government meaningfully addresses longstanding U.S. concerns about its human rights record, as the Uzbek government agreed to do ... but has failed to deliver.”