It's quite hard to get a nuclear bomb to go boom. A lot of things have to happen in a carefully controlled and timed sequence. A big part of that is indeed forc

It's quite hard to get a nuclear bomb to go boom. A lot of things have to happen in a carefully controlled and timed sequence. A big part of that is indeed forcing bits of fuel to stay together for long enough to allow the chain reaction to work its way through a significant proportion of the fuel. Without the force you get various intensities of fizzle explosions and radiation bursts. Hitting the ground with a "doink" after falling out of a plane is more likely to break something than trigger a full-scale explosion.