At the UN's founding in 1945, the Soviet Union became one of the five permanent members of the Security Council.
When in December 1991, the Soviet Union collapsed, the Russia was arguably recognized as the legal successor state of the Soviet Union and maintained the USSR's position on the UNSC.
Here's how the events are usually described (highlights are mine):
In the wake of the collapse of the Soviet Union, 11 Soviet republics […] signed the Alma-Ata Protocol on 21 December 1991 […]. The Protocol provided that the Russian Federation would assume Soviet Union's UN membership, including its permanent seat on the United Nations Security Council. […]
On 24 December 1991, the Soviet Permanent Representative to the UN Yuli Vorontsov delivered to the Secretary-General of the UN a letter from the Russian President Boris Yeltsin. The letter stated that […] Russia would continue the Soviet Union's membership in the UN and maintain the full responsibility for all the rights and obligations of the Soviet Union under the UN Charter.
The letter was circulated among the UN membership without any objection, and Russia formally took over the Soviet Union's seat in the UN General Assembly, in the Security Council and in other organs of the United Nations.
Here's the original text of Alma-Ata Protocol:
- Alma-Ata Protocol at Library of US Congress (English)
- Alma-Ata Protocol at Library of Ukraine's Parliament (Ukrainian/Russian) and also Treaty of CIS foundation, just in case (Ukrainian/Russian)
- Alma-Ata Protocol at Wikisource (Russian)
Unsurprisingly, Alma-Ata Protocol says nothing about UN or UNSC membership. Just noting. Not even stating membership in "international organizations" or something like that.
I also could not find any UNSC resolutions on this matter, but the quotation from Wikipedia suggests that the only valuable document there was Yeltsin's "letter" that "circulated without any objection".
Adopting an UNSC Permanent member seems to be a critical change. Even "less critical" actions, like admitting new UN members, went through adoption of a certain Resolution. For example, three Baltic states were admitted as UN members in the same year of 1991 via UNSC Resolutions 709, 710, and 711. Then, in 1992, more liberated states were also admitted via adopting corresponding UNSC Resolutions 735-739.
- Have the liberated states formally delegated Russia to continue the USSR's membership in the UNSC?
- Is there an UNSC Resolution confirming Russia's seat as an UNSC P5 Member in place of USSR? If so, based on what document(s)?