LAS VEGAS — President Donald Trump defended his tough stance on immigrants crossing the U.S. border with Mexico on Saturday, praising his administration for a job well done and saying his approach will make the United States stronger.Trump also said his peace initiative with North Korea was already paying off despite criticism that his Singapore summit with North Korean leader Kim Jong Un earlier this month was long on positive imagery but short on specific accomplishments.Trump, who was in Las Vegas to lend support to U.S.