Families in Taipei celebrated the annual mid-autumn harvest festival on Monday by watching the full moon over riverside barbecues on Monday. But for several managers at electronics company Wistron, the holiday was off.

“We are running models on the cost of reopening a motherboard production line in Taiwan,” said one. “We have Trump to thank for that.”

Wistron makes the printed circuit boards on which the key electronic components in any device are mounted and connected with each other. Like scores of other Taiwanese manufacturers, it moved most of its lower-technology and labour-intensive production to China beginning in the 1990s. These components are then assembled there or in other countries and built into computers, servers and smartphones.