Photo taken on Feb. 4, 2021 shows a Rafale fighter jet at Tanagra air base in northern Athens, Greece. Four Rafale fighter jets of the French Air Force have arrived at the Tanagra air base to participate in the "Skyros 2021" exercise with Greece from Tuesday to Friday.Photo:Xinhua

Photo taken on Feb. 4, 2021 shows Rafale fighter jets flying over Tanagra air base in northern Athens, Greece. Four Rafale fighter jets of the French Air Force have arrived at the Tanagra air base to participate in the "Skyros 2021" exercise with Greece from Tuesday to Friday.Photo:Xinhua

A Greek pilot is pictured next to a Mirage 2000-5 fighter jet at the Tanagra air base in northern Athens, Greece, Feb. 4, 2021. Four Rafale fighter jets of the French Air Force have arrived at the Tanagra air base to participate in the "Skyros 2021" exercise with Greece from Tuesday to Friday.Photo:Xinhua

Photo taken on Feb. 4, 2021 shows Rafale fighter jets at Tanagra air base in northern Athens, Greece. Four Rafale fighter jets of the French Air Force have arrived at the Tanagra air base to participate in the "Skyros 2021" exercise with Greece from Tuesday to Friday.Photo:Xinhua

Photo taken on Feb. 4, 2021 shows a Rafale fighter jet at Tanagra air base in northern Athens, Greece. Four Rafale fighter jets of the French Air Force have arrived at the Tanagra air base to participate in the "Skyros 2021" exercise with Greece from Tuesday to Friday.Photo:Xinhua