Showing just how unconcerned he apparently is over threatened US sanctions and the recent cancellation of Turkey's participation in the US F-35 program, Turkish President Erdogan is in Moscow on a "shopping trip" of sorts at a moment Russia is delivering the second round of S-400 components to Ankara.

Sukhoi Su-57 fifth-generation fighter jet is inspected by Erdogan during the MAKS-2019 International Aviation and Space Show in Zhukovsky, outside Moscow, Russia, Tuesday, Aug. 27, 2019. Image source: AP

A revealing photo op captured President Putin showing Erdogan the cockpit of a Sukhoi Su-57 stealth fighter jet as Turkey is rumored to be eyeing the Russian advanced fighter as an "alternative" to the F-35 should the blocked transfer of the Lockheed-made fighters become permanent.

Erdogan was in attendance at the MAKS-2019 show in Zhukovsky near Moscow at Putin's invitation to view the next generation fighter in action, the export version of which made its debut Tuesday in the form of the Su-57E.

#Erdogan asks #Putin whether the new Russian fighter jet Su-57 is for sale. Putin answers: "Yes, you can buy". Both laugh. pic.twitter.com/ujUGVxzLp2 — Ali Özkök (@Ozkok_A) August 27, 2019

United Aircraft Corporation (UAC) executives — which designed and produced the Russian stealth jet — had previously offered to start talks with Turkey in the wake of Washington's objections to its S-400 purchase and as the fate of the F-35 looks ever uncertain.

Turkey's foreign ministry had previously called the overture "premature" but said it would weigh all options.

Image source: AP

Erdogan's comments at the airshow were limited to pledging "deepening defense ties" with Moscow and stopped short of commenting on the SU-57 directly.

The Turkish president's visit to Russia is said to be brief, and he was Putin's "guest of honor" at the airshow. Certainly the picture alone of the two leaders at the jet's cockpit is worth a thousand words, no doubt a strong signal to Washington.