Proposed solution to the number of nuclear weapons in the world: Amend the 1963 Partial Test Ban Treaty, which banned nuclear explosions in space, and start using our nukes, cooperatively with other states and under strict regulation, for interstellar travel.
In the 1960’s U.S. Government laboratories, under Project Orion, investigated a pulsed nuclear fission propulsion system. Small nuclear pulse units would be sequentially discharged from the aft end of the vehicle. A blast shield and shock absorber system would protect the crew and convert the shock loads into a continuous propusive force.
The 1963 Partial Nuclear Test Ban Treaty, however, killed the Orion Project, as it “prohibits nuclear weapons tests ‘or any other nuclear explosion’ in the atmosphere, in outer space, and under water.”