US markets modestly higher, closing well off their session highs as traders adopted a cautious stance ahead of President Trump's two-day summit with China's President Xi Jinping and with the US administration alluding to possible some form of action against Syria following the heinous chemical weapons attack in the country earlier this week - Dow up +15-points or 0.07%, S&P500 +0.19% (with Energy leading seven sectors higher), NASDAQ +0.25%.