The endorsement is contained in a communique that the leaders of the 26-nation military alliance will adopt Thursday during their summit being held here, the officials said, speaking on condition of anonymity ahead of the statement's release.

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. It says leaders should come up with recommendations to be considered at their next meeting in 2009, the officials said.