US President Barack Obama is visiting Vietnam and Japan this week, his 10th presidential trip of Asia. It is his farewell tour to a part of the world which he has placed at the centre of his global strategy and economic policy.

President Obama - who was born in Hawaii and who had spent part of his childhood in Indonesia - referred to himself as "America's first Pacific President", stressing that his administration would pursue a US strategic "pivot" from the Middle East to East Asia. That policy took into consideration the growing significance of the emerging markets of the Pacific Rim to American businesses, and was based on the assumption that increasing trade and investment ties with these economies would help strengthen the American economy. The "pivot" also highlighted the need to maintain US military presence in the region in the face of growing Chinese assertiveness vis-à-vis its neighbours that include some of America's leading strategic partners.

From that perspective, Mr Obama's visits to Vietnam and to Japan, where he will attend the G-7 summit in Ise-Shima, underline why expanding American presence in Asia advances US interests and those of the countries in the region.