Re: "Cut the red wire..."
It is possible to design a bomb with 'collapsing circuits' so that if any wire is cut the bomb detonates. That has been true for a long time.You can even include fluoroscopic detectors that might identify attempts to x-ray the device and detonate it. One way the EOD teams used in WW2 to get round this and timers was to pour liquid oxygen into the fuse cavity to freeze clockwork mechanisms and stop current flowing to the detonators.
Modern techniques usually use a container of water that is used to 'disrupt' the device using an small explosive charge to drive a wall of water through the device, disrupting it without sparks an removing thed explosive from the detonator and timing mechanism.