SEOUL—U. S. and South Korean negotiators will meet next week in Seoul to potentially amend a five-year-old trade agreement, which President Donald Trump has called “horrible” and blamed for a larger American trade deficit.

The agreement, known as Korus FTA—which has been in place since 2012—has been a source of tension between the U.S. and South Korea. Mr. Trump has said he would either renegotiate or terminate the deal, which he says has led to American job losses.

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