Palau's president Tommy Remengesau has signed the UN treaty on the prohibition of nuclear weapons.
UN Secretary General Antonio Guterres described the treaty as a product of increasing concern over the risk posed by the continued existence of nuclear weapons, including the catastrophic humanitarian and environmental consequences of their use.
Since it was opened yesterday, more than 50 countries had signed the treaty which comes into effect in 90 days.
Fiji, Samoa, Tuvalu and Kiribati are among the other Pacific Island nations who have signed, while notable exclusions from the region include Guam and the Marshall Islands.
In his address to the UN General Assembly in New York today Mr Remengesau encouraged all world leaders to accede to the treaty.
"Taking into account the recent actions by North Korea we must take seriously the long term need to ban nuclear weapons," said Mr Remengesau.
"I must give credit to the leaders of my country who over 30 years ago recognised the threat of nuclear weapons and banned the use, test and storage of nuclear weapons in Palau's constitution," he said.
"In their honour yesterday I signed this treaty."
Tommy Remengesau also condemned North Korea's threats against Guam describing them as intimidation of the entire Pacific region.