Russia launched the Su-57 fighter jet to hunt and kill US F-35s and F-22s and to export to other countries at a fraction of the cost of US fighters. But so far, Russia has only built one Su-57 with the correct engine, and it could be 2025 before we see just a handful more. Russia said it will not put the Su-57 into mass production at a time where the US has cranked out more than 500 stealth fighters and put them into combat. The Su-57 has failed as anything other than a learning experience for Russia, but Russia has other weapons that can likely down US stealth fighters

Russia's troubled Su-57 "stealth" fighter jet was meant to work as a hunter-killer against US F-35s and F-22s that Moscow could sell around the world, but the program has died an embarrassing death with only one aircraft working as it should.

Russia has just 10 Su-57s today, compared to more than 360 F-35s delivered to the US and partner countries and more than 170 F-22s, and of those jets, only one has the advanced engines meant to power the fifth-generation fighters, The Diplomat's Franz-Stefan Gady reports.

The Su-57, of which Russia said it would have 12 of by the end of 2018, recently had its production delayed, with an order of 13 of the jets, not all of which will have the right engines, pushed back to 2020 and due to for completion within five years, according to The Diplomat.

In short, the Su-57 is not a production aircraft. In its small numbers, it's unlikely to have any meaningful impact on actual warfare.

At best, the Su-57 can serve as a test bed for an innovative array of radars and sensors Russia may likely try to incorporate on older airframes.

Additionally, the Su-57 can help Russia gain experience and understanding in manufacturing stealth aircraft, though the plane itself ultimately falls far short of meaningful stealth.

To date, only the US and China have built true low-observable aircraft.
The Su-57 will not see mass production, Russia announced in 2018, and it can't carry its most formidable weapons without mounting them under the wings, thereby destroying its only hope of radar evasion.

Russia still has a fleet of exceptionally capable fourth-generation fighters and world-class air defences that pose a serious challenge to even the US's best fighter jets, but as for fielding a fifth-generation fighter of its own, Russia has outright failed.