Under terms of the agreement, which went into effect Thursday, the United States will deploy portions of a missile defense shield in Poland by 2018, RIA Novosti reported Friday.
"This agreement is yet another sign of progress for NATO's missile defense system which will defend against current and emerging ballistic missile threats," Rasmussen said in a statement posted on the alliance's Web site.
"The missile defense base will significantly contribute to NATO's capability to provide protection to its European territory, populations and forces against the growing threat posed by the proliferation of ballistic missiles," he said.
Russia has staunchly opposed deployment of missile defense systems near its borders, arguing they would pose a security threat. NATO says the shield is needed to counter the possibility of missile attacks from Iran.
When finished, the shield will be deployed in the Mediterranean Sea, Poland, Romania and Turkey.