Washington, Sep 25 Six Democratic senators have urged President Donald Trump to confront Chinese President Xi Jinping over Beijing’s renewed island-building in the South China Sea, warning that a new outpost could threaten regional countries and restrict US naval operations.Senator Andy Kim of New Jersey led the letter, which was also signed by Senators Tim Kaine, Michael Bennet, Brian Schatz, Tammy Duckworth and Jeff Merkley.The lawmakers sent it to Trump on Wednesday, a day before his summit with Xi began in Washington.They asked Trump to raise China’s activities at Antelope Reef and address what they described as the wider strategic…