[2] In accordance with this goal, Sigur pushed for more openness and a transition to democracy in Asia-Pacific nations throughout his tenure as Assistant Secretary of State.

In applying this mandate he brought a cautious approach to diplomacy, which was based on his extensive knowledge of the cultural sensitivities and history of the East.

He delivered a speech in February 1987 expressing American support for a transition to democracy under a "new political framework," urging South Korea to "civilianize" its military-controlled government.

During his time in office, Sigur sought trade concessions from Japan which included improved access to and openness in the Japanese market,[7] a correction of the yen-dollar exchange rate, and other economic issues.

Members of Congress examined his interactions with Colonel Oliver North and other individuals who were named as being interested in providing financial assistance to the Nicaraguan contras.

[14] At the close of the Reagan presidency, Sigur returned to George Washington University in 1989 as Distinguished Professor of East Asian studies.

As a political conservative and highly respected authority on East Asia and the Pacific, he continued to serve the Republican White House as a part-time adviser throughout Bush’s presidency.

In 1991, in recognition for his profound impact and mark on American international policy towards East Asia, the Gaston Sigur Center for Asian Studies at George Washington University was named in his honor.