NATO says a former US assistant secretary of defense has taken over as the alliance's deputy secretary-general.
Alexander Vershbow replace Claudio Bisogniero of Italy whose term expired this year.
Vershbow, who previously served as a US ambassador to NATO, Russia and South Korea, had coordinated US security and defense policies abroad.
He is the first American to serve in that post. Traditionally, NATO's secretary-general and his deputy are Europeans, while the supreme military commander is a US officer.
Secretary-General Anders Fogh Rasmussen assumed office in 2009.
AP