Obama heads to Asia with 'pivot' plan stymied

US President Barack Obama arrives in the Philippines on Tuesday with his much-vaunted "pivot to Asia" again overshadowed by events in Europe, the Middle East and politics at home.

Obama will touch down in Manila with the world's focus on the murderous attacks in Paris claimed by the Islamic State group and soul-searching about how to counter it in Syria and Iraq.

The long-planned Asia trip had been designed to underscore the US role as a "Pacific power" and timed to coincide with high-profile regional summits, which Obama has made a point of attending.