How would you discourage the proliferation of coal-fired power plants in developing countries?

Would you sign an agreement with North Korea that entailed partial sanctions relief in exchange for some dismantling of its nuclear weapons program but not full denuclearization?

Under what circumstances, if any, would you support the United States joining the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), formerly the Trans-Pacific Partnership?

Would you rejoin the 2015 Joint Comprehensive Plan of Action (JCPOA)? What changes to the existing agreement, if any, would you require before agreeing to rejoin the accord?