Green joined the Ministry of Foreign Affairs in 1970, after graduating from the University of Canterbury.
In 1978, Green was posted as first secretary to New Zealand's mission to the United Nations in New York.
In 1988, Green was appointed director of the External Assessments Bureau, a section of the Department of Prime Minister and Cabinet, where he spent six years.
Following his return from Jakarta, Green was appointed Deputy Secretary at the New Zealand Ministry of Foreign Affairs and Trade, responsible for New Zealand's security policy and responsibilities for the Americas, North Asia, and South and South-East Asia.
[2] In addition, New Zealand police officers were refused Fijian visas to escort Green back to New Zealand, and a Fairfax Media journalist, Michael Field, was detained then deported by Fijian immigration authorities when he arrived to cover the story.