The Organisation for the Prohibition of Chemical Weapons (OPCW) has just announced the accession of Angola to the Chemical Weapons Convention (CWC). The country deposited its instrument of accession with the UN Secretary-General on 16 September, which means that it will become a party to the CWC 30 days later, that is, 16 October.
Angola will thus be the 192nd state to join the OPCW. No other treaty limiting possession or use of a particular type of weaponry can boast that many parties. The Non-Proliferation Treaty (NPT) has 191; the Biological and Toxin Weapons Convention (BTWC) 173.