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The Japanese terrorist cult Aum Shinrikyo -- which launched the infamous Sarin gas attack on the Tokyo subway system in 1995 -- was discovered to have experimented with the use of lasers as weapons . According to The Asian Pacific Post , " Cult members apparently obtained laser design information from Russian institutes they visited and built a laser weapon mounted on a truck .
 which: attacker; Tokyo: place; system: target; gas: instrument
Given event type and trigger, please tell me the arguments of all the listed option. Output format is "name1: role1; name2: role2". 
Event type: attack 
  Option: victim, attacker, place, target, instrument 
Text: {0} 
Answer:
 which: attacker; Tokyo: place; system: target; gas: instrument