Officials say Petraeus is meeting with Secretary-General Anders Fogh Rasmussen and will address the North Atlantic Council, the alliance's top decision-making body, on Thursday.
He will likely try to smooth ruffled feathers among European allies contributing troops to the 122,000-strong international force. Diplomats say member governments were not consulted about the changeover in command after President Barack Obama's sudden dismissal of Petraeus' predecessor, Gen. Stanley McChrystal.
U.S. troops account for most of the 122,000-strong international force in Afghanistan. European and other allies make up about a third of the force.