The head of Nato apologised on Friday over a training exercise in Norway after Turkish President Recep Tayyip Erdogan withdrew troops in protest at an incident he deemed offensive.
Erdogan said he had ordered the 40 troops to be removed from the exercise -- a desktop drill not involving boots on the ground -- after an image of the founder of modern Turkey, Mustafa Kemal Ataturk, and his own name were included as "targets".
Nato Secretary General Jens Stoltenberg, a former Norwegian prime minister, apologised for upsetting Turkey, a key member of the alliance but one which has caused disquiet recently with its increasingly close relations with Russia.
"I apologise for the offence that has been caused. The incidents were the result of an individual's actions and do not reflect the views of Nato," Stoltenberg said in a statement.
"Turkey is a valued Nato ally, which makes important contributions to allied security."
The Trident Javelin exercise in Stavanger, southern Norway, is described on a Nato website as a "computer assisted exercise without troops on the ground", aimed at improving command structures for big operations.
The decision by Ankara, a Nato member since 1952, to buy the S-400 air defence system from Russia caused concern among its Western allies, but Turkey remains an important and active member of the alliance.
Stoltenberg was at pains to stress that the individual responsible for the incident was not one of Nato's staff.
"He was a civilian contractor seconded by Norway and not a Nato employee," Stoltenberg said.
"It will be for the Norwegian authorities to decide on any disciplinary action. Nato has been in contact with the Norwegian authorities on this issue."