BAKU (Reuters) The United States sought to shore up a link in its supply chain to Afghanistan on Sunday, sending Defence Secretary Robert Gates to Azerbaijan, a transit point that has complained about not getting enough attention. Since 2001, tens of thousands of military aircraft and supply trucks have crisscrossed Azerbaijan by air and land, carrying US and NATO forces and equipment to the war zone. The Pentagon wants to make sure there are not any problems that could slow President Barack Obamas 30,000-troop surge. As part of the Obama administrations campaign to keep Azerbaijan on board, Gates sandwiched a less than 24 hour stop in Baku, the capital, in between talks in Asia and Europe about the crisis on the Korean peninsula and the war in Afghanistan. He said the trip was spurred, in part, by concerns in Azerbaijan that we werent paying enough attention to them. Its important to touch base and let them know that in fact they do play an important role in this international coalition, Gates told reporters on his plane before landing. To underline the message that the United States was paying more attention to Azerbaijan, Gates will hand deliver a letter to President Ilham Aliyev from Obama to make clear we have a relationship going forward, a senior defence official said. Gates is the first cabinet-level official to visit Azerbaijan since Obama came to office last year, and he made clear more high-level exchanges were planned. The United States wants to expand military-to-military relations, from training to exercises, officials said. As part of the outreach effort, the Pentagon sent a senior defence official to meet with the Azeris and US Secretary of State Hillary Clinton has spoken by phone to Aliyev. Officials said Azerbaijan told the Pentagon it was concerned about not getting higher-level visits and about not seeing the fruits of what the United States calls their strategic partnership. The complaints were more about 'Why arent you taking our concerns seriously? You need to show us that youre taking our concerns seriously. So we got the message, the senior defence official said. You cant argue with perceptions. They are what they are. And so weve been trying to redress that. Aliyev has been particularly critical of Washingtons role in its festering conflict with Armenia over the breakaway mountain region of Nagorno-Karabakh.