Article 93 Chicago Convention

Admission of other States

States other than those provided for in Articles 91 and 92 (a) may, subject to approval by any general international organization set up by the nations of the world to preserve peace, be admitted to participation in this Convention by means of a four-fifths vote of the Assembly and on such conditions as the Assembly may prescribe: provided that in each case the assent of any State invaded or attacked during the present war by the State seeking admission shall be necessary.

See also: Article 92 Chicago Convention