The United States this month convened a meeting of working-level experts from China, France, Russia and the United Kingdom to discuss nuclear weapons issues including strategic risk reduction, the State Department said.
The department said Washington hosted the meeting on June 13-14 in Cairo among the five nuclear weapons states, describing it as "an ongoing exchange in the context of the Nuclear Non-Proliferation Treaty (NPT)."
The experts were drawn from the countries' respective ministries of foreign affairs and defense, the department said. They "discussed strategic risk reduction, as well as nuclear doctrines and policy," it added.
What is the NPT?
The NPT, which took effect in 1970, aims to halt the spread of nuclear weapons-making capability and guarantee the right of members to develop nuclear energy for peace means.
The treaty allowed the five nuclear weapons states - who are the permanent members of the United Nations Security Council - to keep their nuclear arsenals.