The international dimensions of terrorism had been identified prior to World War II. Nonetheless, no agreement could be reached on an acceptable definition, or appropriate action, and the 1937 Convention on the Prevention and Punishment of Terrorism, adopted by the League of Nations, was ratified by a single country. The issue resurfaced in the late 1950s when private individuals perpetrated an alarming number of incidents endangering civil aviation during transnational flights. These incidents led to the adoption of three distinct conventions on the subject, namely the 1963 Tokyo Convention on Offenses and Certain Other Acts Committed on Board Aircraft, the 1970 Hague Convention for the Suppression of Unlawful Seizure of Aircraft, and the 1971 Montreal Convention for the Suppression of Unlawful Acts Against the Safety of Civil Aviation.