TAIPEI—Taiwan and the United States have mutually beneficial trade relations especially in technology, and the two have “smooth” communication channels and will keep talking to each other on currency issues, Taiwan’s central bank said on Saturday. Taiwan, along with Vietnam, again exceeded the U.S. Treasury’s thresholds for possible currency manipulation and enhanced analysis under a 2015 trade law, but the department on Friday refrained from formally branding them as manipulators. Responding, Taiwan’s central bank reiterated the trade surplus with the United States was due to the China–U.S. trade war, which has seen companies shift production from China to avoid tariffs, and soaring tech demand from U.S. consumers during the COVID-19 pandemic. “The expansion of the trade surplus with the United States has nothing to do with exchange rate factors,” it said in a statement, repeating comments from a central bank official late Friday. Taiwan’s current account surplus has also been …