I had the idea of fusing Jupiter in 1973. I was learning about nuclear reactions and wondered what it would take. The first thought is to use a thermonuclear device, but can it reach a depth where ignition would be self-sustaining? The US military hoped that the Earth would not ignite when they did the first H-bomb test. Hydrogen bombs use Lithium and Deuterium fusing in the flash plasma of the uranium or plutonium fission device (or so I recall). Maybe if one packs a large enough quantity of LiD2 ? The mainly hydrogen composition of Jupiter may be less inclined to fuse unless temperature and compression are still hotter that a nuke can provide. If so, a bomb won't do it. The crashing of comets into the Jovian surface yield terrific scars from the burn-up, and I'm sure Jupiter has seen much worse. Thermal or thermonuclear explosions probably can't start it. So yeah, you need a million obelisks.