UNITED NATIONS (AP) – The United Nations says the 191 parties to the Nuclear Nonproliferation Treaty have decided to postpone a conference to review its implementation because of the coronavirus pandemic. The treaty is considered the cornerstone of global efforts to prevent the spread of nuclear weapons and the parties hold a major conference every five years to discuss how it is working. The meeting was scheduled to be held from April 27-May 22 at U.N. headquarters in New York. U.N. spokesman Stephane Dujarric said the review conference will be held “as soon as the circumstances permit, but no later than April 2021.