Since allegations of Pyongyang's nuclear weapons programme first surfaced in the early 1990s, Chongryon has frequently reported being targeted by hate mail, malicious phone calls, and numerous incidents. Chongryon facilities have also frequently been sites of protests by Japanese right-wing groups. There have been numerous incidents of students of Chongryon schools, identifiable by their uniforms based on traditional Korean costumes, suffering verbal abuse. Furthermore, around May and June 1994 there was a series of physical assaults on Chongryon students in which their uniforms were cut; this was reported heavily in the Japanese media and triggered a Ministry of Justice investigation. The investigation determined that the students had cut their own uniforms. In 1998, a petrol bomb was thrown at Chongryon's headquarters in Tokyo, causing minor damage. In June 2003, a shot was fired into a Chongryon warehouse in Niigata, hitting cargo waiting to be loaded onto Mangyongbong-92. In October 2006 in the aftermath of North Korea's first nuclear test, a suspected arson attack damaged a bamboo grove inside Chongryon's school in Mito. A 15-year-old female student was pelted with eggs at the school the same day.