missile, Kh-59MK2 according to available information, is almost entirely a new development and is essentially an analog of the famous western KR same class AGM-158 JASSM, Scalp EG / Storm Shadow and Taurus.
Yes it is for sure in the same class and show very similar concept of operation with those foreign cruise missiles.
Someone, anyhow, should remind that all those three weapons presented for the first time and in spotlight at МАКС-2015 in the КТРВ stand (in theirs exportable version : "Х-59МК2", "Гром-Э1" and "Гром-Э2") boast a particular and very important feature that distinguish markedly theirs design : those weapons are all compatible with internal weapon bay of ПАК ФА
Not even one western cruise missile, still at today, is compatible with internal carriage ,both in F-22 and F-35, a factor that not only reduce significantly the effective combat range of the delivering aircraft ,but render attacks to critical enemy installations in the deep of enemy territory much more difficult, if not impossible, because the radar footprint of enemy air defenses and interceptors will be not "reduced" in any way (obviously is necessary to add at what just said that the significantly higher cruise speed that ПАК ФА will be capable to maintain ,in comparison to F-35, in similar strike missions will furtherly reduce the effective SAM/aircraft interception's footprint).
For what concern "Гром-Э1" and "Гром-Э2", i have noticed that several debates has been arisen by those weapons ; in particular several people fail to identify what feature of those weapons induce the makers at ГНПЦ «Звезда-Стрела to show so much pride for the design.
The element in question is represented by the, at now, unparalleled fraction of warhead's weight on the overall weapon mass.
"Гром-Э1" and "Гром-Э2"are export versions (MTCR compliant) of air to ground weapons purposely conceived for the specific dimensions of ПАК ФА weapon bays and altitude and speed of delivery from this Platform; them are in the same class of US JSOW and JSOW-ER (the unique western products in the class to be qualified for internal carriage on F-35).
Just for comparison a JSOWs (unpowered version) that in future will be mounted in the internal bays of F-35 have a warhead weight of maximum 500 lb (about 226 kg), a "Гром-Э2" (unpowered version ) at similar weapon weight will boast a warhead mass almost double of that !
In substance a single ПАК ФА armed with a similar weapon will be capable to deliver on a target destructive power (at significantly expanded delivery range, thanks to the higher speed of the carrying aircraft and the weapon's aerodynamic layout optimized for supersonic release and...propulsion) almost equal to that delivered by two F-35 with its JSOWs .
The powered version -Гром-Э1- has ,still at today, not a western equivalent in F-22/F-35 internal weapon's selection.