By Jeff Mason, Bart H. Meijer and David Brunnstrom WASHINGTON/BRUSSELS (Reuters) -U.S. President Donald Trump opened a new phase on Monday in the trade war he launched this year, telling partners, from powerhouse suppliers such as Japan and South Korea to minor players,

The country’s new president, in office for a little over a month, had just dispatched his senior deputies to Washington to try to work out a trade deal.