SEOUL, May 21 (Reuters) - President Joe Biden said on Saturday the 70-year alliance between the United States and South Korea was built on opposition to changing borders by force, and working together to deter North Korea and keep the Indo-Pacific region free and open.

Biden made the comment at a summit with South Korea's new President Yoon Suk-yeol, during which Yoon said the transformation of trade and supply chains provided further reasons to develop the alliance.