Updated

With momentum toward international adoption of a nuclear test ban treaty stalled, representatives of more than 100 countries are urging holdouts to ratify the document.

Leaders convened at the United Nations General Assembly Thursday to mark fifteen years since the treaty was negotiated and to press remaining countries to bring it into force.

The Comprehensive Nuclear Test Ban Treaty has been signed by 182 countries and ratified by 155 of them. But it needs to be ratified by all 44 states identified as nuclear technology holders to enter into force.

Nine have not yet done so -- China, North Korea, Egypt, India, Indonesia, Iran, Israel, Pakistan and the United States.

U.N. chief Ban Ki-moon told the delegates the ban was "an indispensable stepping stone to a nuclear-weapon-free world."