I assume they discovered the need for an anti-theft alarm after the test machines were deployed? So how many did they lose? Who has them? Not that the last point would mean much if they don't work.

Operational failure at night? Maybe they were lured away by extremely attractive North Korean Robotic Seductresses flashing their gear(s). "Hi soldier. Lonely out here at night, isn't it?"

Who knows what these machines get up to when we're not looking.

All they need to do is hire all the droids that enforce the parking regs in my city. They move like greased lightning, nail the perps every time and are completely merciless.

The merkins have a robot sentry that doesn't work, but they don't really have a need for it anyway. The South Koreans have a robot sentry line that doesn't work, but they don't actually need one either. Honestly, North Korea is just posturing and it would seem that no one is taking him seriously.

The Israelis have a robot sentry line, and they think they need it like they need to breath.

Is it any wonder which sentry line is actually working ?

I think not.

.....and immediately imagined hordes of pasty, overweight robotic sentries doing pushups and running round an assault course while being yelled at by a stroppy Korean drill-sergeant in an attempt to get them "fit for combat".

Given that N and S Korea aren't in a shooting war, how does deploying these warbots along the border for a year constitute a trial, and how does one judge said bots a failure? Didn't they fill their quota for shooting border jumpers? Or if they just sat there doing nothing for a year, well, isn't that what they're supposed to do, until Pyongyang decides to invade?

I suppose there is the possibility that they spent the whole year firing on non-existent targets, or worse, friendlies.

Shame it sounds like they are being wholesale replaced rather than upgraded, since everyone knows all you have to do to upgrade an automated sentry gun turret is have one of your engineers whack it several times with a large wrench.