BRUSSELS—Since a failed coup in July, Turkey has recalled half of its military officers assigned to commands overseen by the North Atlantic Treaty Organization’s top commander, officials said Wednesday.

U.S. Army Gen. Curtis Scaparrotti, NATO’s Supreme Allied Commander, Europe, said 150 of the 300 Turkish officers serving in several key military commands of the alliance had been summoned back to Turkey and about half have been replaced.

Turkey’s military chief, Gen, Hulusi Akar, has pledged to refill all the slots in NATO allotted for Turkey, Gen. Scaparrotti said. He and other NATO officials said, however, that many of the new officers have far less experience, raising concerns that they will undermine the alliance’s work.

The 150 recalled officers were assigned to NATO’s Supreme Headquarters Allied Powers Europe in Mons, Belgium, Allied Joint Force Command Brunssum in the Netherlands and Allied Joint Force Command Naples in Italy, all of which are staffed with more senior officers.

Thousands of soldiers suspected of involvement in the coup attempt have been arrested, and according to alliance officials, Turkish officers summoned back to Turkey have faced expulsion from the military and the loss of benefits, and some have been jailed. Their number isn’t known.