Not exactly. Both no-first-use and sole purpose restrict the option of launching a nuclear strike to only those circumstances involving a threat from nuclear weapons. However, sole purpose would provide an option of a pre-emptive first strike against a nuclear threat, while no-first-use would rule out such a pre-emptive strike, providing for a nuclear strike only if one had already been attacked by nuclear weapons. Adoption of sole purpose policies could be seen as an interim step towards no-first-use or a comprehensive prohibition on any use.