An Israeli satellite revealed images Saturday of Russia's deployment of its Sukhoi Su-57 stealth planes in Syria – the first of its kind.

The satellite operator iSi said in a statement that their Israeli Eros B satellite spotted two such planes at the Khmeimim air base. It said the Su-57 is still not fully operational and that Russia is likely going to use Syria as a "playground" for testing the jet.

>> The one reason Putin deployed the stealth fighters in Syria

Open gallery view Putin's stealth fighters - the Su-57 Credit: Alex Beltyukov - http://www.airliners.net/photo/Russia---Air/Sukhoi-T-50/2002344/L

A few days ago, Russian news reports said that Moscow had beefed up its forces in Syria with several warplanes, including its latest fighter jets.

This is the first time the planes have been seen in Syria and it is unclear if Russia plans to use them in attacks, as they are still going through developmental stages.

The Su-57 is considered a "fifth generation", a class that includes the F-22 and the F-35 – which was procured by Israel – to which the Russian plane is supposed to be a response to.

Russian Deputy Defense Minister Yuriy Borisov said in an interview in early February that the Su-57 had concluded the first trial stage, and noted that combat trials would proceed according to schedule.

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The Kremlin on Thursday that it wouldn't comment on the reports, referring questions to the military, which remained mum about the deployment.