US Vice President Joe Biden has stressed his country\'s position that Japan and China should each take necessary measures to ease tensions over the disputed Senkaku islands in the East China Sea. Biden met Japanese Prime Minister Shinzo Abe in Singapore on Friday. They are respectively visiting the country. Biden said he reconfirms where the United States stands over the Senkaku issue, including its responsibility as Japan\'s ally. The islands are controlled by Japan, but claimed by China and Taiwan. Abe said Japan has left a door open for dialogue with China. Abe also spoke on the Trans-Pacific Partnership free trade negotiations. He said the TPP is critically important in economic terms, as well as from a strategic viewpoint of solidifying the Japan-US alliance, Japan\'s (NHK World) reported. He expressed hope that the two countries will work together in coming rounds of negotiations to make their ties even closer. Biden said successful TPP negotiations are essential as the US administration focuses its political strategy on the Asia-Pacific region, where Japan is expected to play a major strategic role