816
North Korea ' s military may have fired a laser at a U . S . helicopter in March , a U . S . official said Tuesday , as the communist state ditched its last legal obligation to keep itself free of nuclear weapons .
 ( attack: fired,  military: attacker, helicopter: target, laser: instrument) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: declare bankruptcy, transfer ownership, transfer money, marry, transport, die, phone write, arrest jail, convict, sentence, sue, end organization, start organization, end position, start position, meet, elect, attack, injure, born, fine, release parole, charge indict, extradite, trial hearing, demonstrate, divorce, nominate, appeal, pardon, execute, acquit, merge organization, Arguments type: beneficiary, prosecutor, plaintiff, seller, victim, buyer, agent, destination, artifact, organization, recipient, person, place, origin, target, giver, adjudicator, attacker, vehicle, defendant, entity, instrument. 
Text: {0} 
Answer:
 ( attack: fired,  military: attacker, helicopter: target, laser: instrument) 