The New York Times published an analysis that it said revealed Iran's development of its air force and preparations for it to receive the Russian Sukhoi 35 fighter.
The newspaper said that it relied, in its analysis, on photos, videos, and satellite images.
One of them showed - according to the newspaper - that it was a life-size model of the Russian fighter plane.
It was also based on drawings that appeared in a video clip published by the Iranian armed forces of a new underground air base, where the drawings of the aircraft resemble the design of the Sukhoi 35.
The American newspaper published satellite images that it said were of an air base in a mountainous area in Hormozgan Province (southern Iran).
On the seventh of this month, the Iranian army unveiled the first underground military air base, called "Oqab 44".
According to information provided by the Iranian army, the base dug deep in the mountains is capable of storing and operating different types of combat aircraft, bombers and drones.
A video clip published by a local Iranian channel showed a visit by the Chief of Staff of the Iranian Armed Forces, Major General Muhammad Bagheri, and the Commander-in-Chief of the Iranian Army, Major General Abd al-Rahim Mousavi, to the base, which also contains hangars for warplanes, a center for repair and maintenance, and fuel tanks, in addition to a warning area and a command center.