MOSCOW - The Kremlin said on Sunday that inflexibility on the part of the United States was to blame for the lack of a bilateral meeting between Russia's President Vladimir Putin and US President Donald Trump during a summit in Vietnam.Trump and Putin met briefly on the sidelines of the Asia-Pacific Economic Cooperation summit in Vietnam on Saturday and agreed on a joint statement supporting a political solution for Syria, but did not hold substantive bilateral talks."Unfortunately the American side did not offer any alternatives despite all efforts of our Russian colleagues. There was only one time offered that was convenient for the American side, and only one place offered, which had already been rented by the Americans," Kremlin spokesman Dmitry Peskov was quoted as saying by the RIA news agency."The Americans showed no flexibility, and unfortunately did not offer any other alternative proposals. That is why the meeting could not happen," Peskov added.