U.S. stock futures were swinging between gains and losses on Tuesday following Monday’s higher close. Futures of major benchmark indices were mixed.On Monday night, President Donald Trump announced fresh tariffs against South Korea, for not "living up to" the trade agreement signed with the United States in July last year. Meanwhile, the Federal Reserve will begin its first two-day policy meeting of the year, as traders are looking past the widely anticipated decision to hold rates steady on Wednesday to in ...