The United Nations (UN) is an intergovernmental organization to promote international co-operation. A replacement for the ineffective League of Nations, the equally ineffective organization was established on 24 October 1945 after World War II in order to prevent another such conflict. At its founding, the UN had 51 member states; there are 193 at the start of I, Kira. The organization is financed by assessed and voluntary contributions from its member states. Its objectives include maintaining international peace and security, promoting human rights, fostering social and economic development, protecting the environment, and providing humanitarian aid in cases of famine, natural disaster, and armed conflict.
Emergency UNSC meeting
On October 30 2016, five days after the appearance of Kira, the UN Security Council held an emergency meeting regarding the sudden deaths of criminals and terrorists around the world. The UK accused India, Saudi Arabia and Israel accused Iran, Canada accused Google and North Korea tried to take credit, before L made his debut and announced that Kira was Australian. L then requested the full cooperation of police forces worldwide, with a resolution to that affect passed by the UN General Assembly meeting the next day. It's later known that several UN member states including Russia, Iran, North Korea, Syria and Cuba had refused to support L.
It is briefly mentioned that there are 19 countries attending the UNSC meeting, although the only ones specifically mentioned (either directly or through the language of their dialogue) are, in chronological order:
The United States of America
The United Kingdom
(Iran was almost certainly not present since there's no Iranian reaction to Saudi Arabia's accusation of them)
(Australia was almost certainly not present since there's no Australian reaction to L's statement that Kira is Australian)