The Huffington Post published the document Wednesday night in conjunction with a Danish newspaper.
The document suggests that the NSA planned to spy on leaders and negotiators before and during the conference in Copenhagen in December 2009.
Signals intelligence would play “a significant role,” according to the document, in keeping “our negotiators as well informed as possible” during the two-week meeting. The Huffington Post notes signals intelligence encompasses both emails and phone calls.
Second Party partners are foreign agencies from Canada, Australia, New Zealand and United Kingdom that share intelligence with the United States.
President Obama and other world leaders attended the meeting. Delegates were convening to discuss how to limit greenhouse gas emissions.
"[L]eaders and negotiating teams from around the world will undoubtedly be engaging in intense last-minute policy formulating; at the same time, they will be holding sidebar discussions with their counterparts -- details of which are of great interest to our policymakers," the document reads.
Obama and then-Secretary of State Hillary Clinton were among those would have likely been briefed about the information collected, the document also notes.
The document is just one of the latest leaks by former NSA contractor Snowden, who has been living in Russia since last August. U.S. intelligence officials stressed to congressional panels on Wednesday that his leaks have caused enormous damage to national security.