Later he was the spokesperson of the Ministry of External Affairs and the Prime Minister's Office.

In 1968, he joined the Indian Foreign Service, and his first diplomatic assignment was as the Third Secretary in the Embassy of India in Moscow from August 1970.

For years he was known in the corridors of South Block (Secretariat Building) as "Chotta GP" ('chotta' is Hindi for small) to distinguish him from his namesake G Parthasarathy one of India's tallest diplomats, who served as India's High Commissioner to Pakistan between 1963 and 1965.

[4] He currently writes an influential column in The Pioneer, Business Line and Rediff.com,[5] mostly on foreign affairs.

[6][7] He co-authored a book with ex-Pakistan Foreign Secretary, Humayun Khan.