Muscovites have the balls but not the money
In previous reports, Perminov has been quoted as saying that the "engine" design now being worked on is of the type known as "megawatt-class nuclear space power systems" (MCNSPS). This refers specifically to use of a nuclear reactor to generate electricity, but other previous remarks regarding a propulsion capability suggest that the Russian engine could also use reactor heat to eject reaction mass, providing thrust as well as electrical power. Reactors normally generate a large surplus of heat energy over and above their electrical output, so the scope is there to do both propulsion and power generation at once: nuclear rockets using reactors to heat reaction mass were tested decades ago. Because they can use reaction mass selected to be good reaction mass – rather than being forced to accept what chemical fuels can produce – they can get much more shove out of a given weight of fuel.
Source: theregister.co.uk