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Whisteblower Edward Snowden had previously leaked documents in 2013 that alleged the NSA had carried surveillance of the Brussels - based Society for Worldwide Interbank Financial Telecommunication ( Swift ) for several years , but did not specify how .
 ( data breach: had previously leaked,  Whisteblower Edward Snowden: attacker, documents: compromised data, 2013: time) 
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: phishing, data breach, ransom, discover vulnerability, patch vulnerability, Arguments type: vulnerable system, capabilities, vulnerability, number of victim, issues addressed, compromised data, damage amount, common vulnerabilities and exposures, victim, patch number, number of data, tool, discoverer, time, purpose, place, payment method, releaser, vulnerable system version, attacker, supported platform, patch, price, vulnerable system owner, trusted entity, attack pattern. 
Text: {0} 
Answer:
 ( data breach: had previously leaked,  Whisteblower Edward Snowden: attacker, documents: compromised data, 2013: time) 