As Director-General of the North American Affairs Bureau, Song headed the Second U.S.-Korea Revised SOFA negotiations (1999–2000), successfully improving upon the previous agreement in seven fields, including environmental protection and criminal trial procedures.

In December 2000, Song led the U.S.-Korea Missile Technology Control Regime (MTCR) negotiations, and in March 2001, he was appointed ROK's Ambassador to the Republic of Poland.

During his time as National Security Adviser, Song was accredited to have successfully handled two major foreign policy crises: North Korea's missile launching incident in July and its first nuclear test in October.

Another major area of interest has been the settlement of North Korean defectors in South Korea who are currently not receiving adequate vocational training.

His major legislations so far have been: In seeking to enhance Korea's global standing and accelerate inter-Korean reconciliation, Song continues to collaborate with colleagues within and without the National Assembly in a principled and bipartisan manner.