Can nuclear powers fight a long conventional war?

Is a long war between nuclear powers realistic?

It can be if the conflict remains geographically distant and limited or proxy-based; direct threats to homeland territory make prolonged restraint far less likely.

A direct war over territory bordering both nuclear powers is judged unlikely to remain limited for long. A dispute distant from both homelands could continue because neither side wants to expose its own territory to nuclear attack. The Korean War introduces a qualification: China was not nuclear-armed at the time. The Soviet Union supplies the nuclear-power comparison, but its involvement is described as indirect, making Korea an example of proxy conflict rather than an uncomplicated case of direct war between nuclear powers.