By Jeff Mason and Leika Kihara WASHINGTON/TOKYO (Reuters) -Powerhouse Asian economies Japan and South Korea said on Tuesday they would try to negotiate with the U.S. to soften the impact of sharply higher tariffs that President Donald Trump now plans to impose from the start of August.

The Trump administration initially announced the global tariffs on April 2 before opting to pause he bulk of the levies a week later in favor of a July 9 date.

President Donald Trump has issued a sharp warning to 14 countries: unless they strike new trade agreements with the U.S., steep reciprocal tariffs between 25% and 40% will come int