Despite a setback in his drive to see NATO expanded further eastward to include Ukraine and Georgia, Bush vowed not to drop the issue.

“NATO’s door must remain open to other nations in Europe that share our love for liberty and demonstrate a commitment to reform and seek to strengthen their ties with the trans-Atlantic community,” Bush said in brief remarks at an alliance meeting. “We must give other nations seeking membership a full and fair hearing.”

Fellow NATO leaders, fearing a clash with Moscow, rejected Bush’s appeal to allow the former Soviet republics to get on a path toward membership. But Bush’s national security adviser, Stephen Hadley, said the president plans to make a new pitch before he leaves office in January. The United States expects to raise the matter at a meeting of NATO foreign minister in December, Hadley said.

Progress on missile defense represented perhaps the biggest boon to Bush from the summit. Russia has strongly opposed the plan.

NATO leaders were adopting a communique stating that “ballistic missile proliferation poses an increasing threat to allied forces, territory and populations.” It also will recognize “the substantial contribution to the protection of allies . . . to be provided by the U.S.-led system,” according to senior American officials.

The statement calls on all NATO members to explore ways in which the planned U.S. project, to be based in Poland and the Czech Republic, can be linked with future missile shields elsewhere.