From the Japan Times (link):
Among the noncultural things that Russian President Vladimir Putin did in China recently was to sign agreements to build two pipelines to carry Russian gas to west China. This was just a week before the Chinese signed an agreement with Turkmenistan for another pipeline to carry even more gas to west China.
This irked the Russian leaders as they regard the Turkmens as their own supplier of cheap gas. The contract could have been a slap in the face to the Russians for continuing to refuse to commit themselves to build an oil pipeline from Siberia into China as they keep open the option of supplying Japan instead.
Putin is applying a policy of triangulation between China and Japan, letting them both think that he will favor them in the final settlement of the direction of the pipeline. He will have to come off the fence eventually, but while he continues to sit he is upsetting both countries.