The United Kingdom's permanent Security Council seat, its founding place in NATO and the Commonwealth it helped create
Background
The United Kingdom delivered a statement at the UN Security Council on Russia's intensifying attacks on Ukraine, which it can do as a permanent member. The memberships behind that are these.
The United Nations lists the five permanent members of the Security Council as China, France, Russian Federation, the United Kingdom and the United States.
NATO lists the United Kingdom as a member since 1949, when the North Atlantic Treaty was signed in Washington, D.C. on 4 April; the United Kingdom was one of the twelve founding members and the alliance now has 32 member countries.
The Commonwealth records that the United Kingdom joined in 1926, when it helped found the British Commonwealth of Nations, and that King Charles III is Head of the Commonwealth as well as Head of State of 15 Commonwealth countries.
In plain words
Permanent member Permanent member of the UN Security Council — One of five states with a permanent seat and the power to veto a substantive Council decision.
North Atlantic Treaty North Atlantic Treaty — The 1949 treaty signed in Washington, D.C. that created NATO.