"The US is ready to support Montenegro's aspirations to join NATO and other international integrations," Rumsfeld said at a joint press conference with Montenegrin Prime Minister Milo Djukanovic.
Djukanovic said Montenegro was interested in enhancing cooperation with the US in military, political and economic areas.
Rumsfeld was the first US government minister to visit independent Montenegro.
According to announcements from the Pentagon, the purpose of his visit was to obtain Montenegro's support for the global fight against terrorism and to discuss the country's possible assistance to US-led peacekeeping missions, particularly those in Iraq and Afghanistan.