NATO leaders have invited Bosnia-Herzegovina, Montenegro and Serbia to join the alliance's Partnership for Peace program.
NATO earlier had excluded Bosnia and Serbia from the program because of their failure to arrest and extradite former Bosnian Serb leader Radovan Karadzic and his top military commander Ratko Mladic.
The United Nations war crimes tribunal in The Hague indicted both men for their role in attacks on civilians during the Bosnian conflict.
In Belgrade, Serbian President Boris Tadic welcomed the decision, saying it will benefit Serbia's economic recovery and pave the way for further reforms.
However, U.N. war crimes prosecutor Carla del Ponte said she is "surprised and disappointed" by the action.
In a statement at the alliance summit in Riga, Latvia, NATO again urged both Bosnia and Serbia to fully cooperate with the Hague tribunal.
The NATO program calls for cooperation with partner countries without giving them alliance security guarantees.
The NATO leaders say they plan to issue invitations in 2008 for full alliance membership to European countries that meet alliance requirements.
The alliance specifically praised Albania, Croatia and Macedonia for implementing needed reforms.
Some information for this report was provided by AP and Reuters.