Government officials on Friday rushed to analyze the implications of Philippine President Rodrigo Duterte's surprise announcement that his nation was "separating" from the United States but publicly played down any impact ahead of his planned visit to Tokyo starting Tuesday.

Prime Minister Shinzo Abe has long tried to strengthen Japan's ties with the Philippines in an attempt to keep China in-check following territorial disputes in the South China Sea.

But in Beijing on Thursday, Duterte reportedly announced both economic and military "separation" from the United States, Japan's sole military ally.