NATO countries have been slow recently to meet needs for more coalition forces, and Rumsfeld has been meeting with defense ministers in southeastern Europe to remind them of their commitment.
Many of the countries at the conference have signed a Partnership for Peace Agreement with NATO, which is seen as a stepping stone to eventually becoming a full member of the alliance.
"I have every confidence that NATO is fully committed in Afghanistan and that the requirements ... will be filled by NATO and the Partnership for Peace nations because success in Afghanistan is important to Europe," Rumsfeld told a news conference here. "It is important to Asia."
NATO-led troops are in command of the southern portion of Afghanistan and are expected to take over the eastern section -- which U.S. troops now command -- later this year.
After meetings here that also touched on military cooperation in the Balkans, Rumsfeld was traveling to a NATO defense ministers meeting in Slovenia, where the focus will be on continued violence in Afghanistan and NATO involvement there.
Albanian military officials declared their unequivocal support for America's battle against terrorism. And Montenegro's prime minister said his small country would like to participate in peacekeeping operations. Albania has 120 troops in Iraq.
Both Albania and Montenegro are working to gain admission to NATO and other international groups, and the U.S. has pledged to support their efforts.
Montenegro Prime Minister Milo Djukanovic made no firm commitment to supply troops to either Iraq or Afghanistan, but said his country "prepared to participate in the U.S.-led coalition in fighting terrorism."